Parent-offspring Interactions Research Articles

Mine or my neighbours’ offspring: an experimental study on parental discrimination of offspring in a colonial seabird, the little auk Allealle

Individual recognition (IR) abilities may result from various ecological and naturally selected features of a species. Complex IR mechanisms should develop when the risk of misidentification of a chick is high. For colonial seabirds, the ability to identify their own brood is crucial to ensure parental fitness. Vocalizations seem to be a key component of most parent–offspring interactions, although few studies have assessed the interindividual differences in seabird chick calls and their potential usage in IR. The little auk (Allealle), which breeds in dense colonies, constitutes a perfect model for testing IR. In this study, we (1) examined chick calls at different stages of the nesting period, and (2) cross-fostered chicks to examine the rate of acceptance/nonacceptance of chicks by parents. We found significant interindividual differences in chick begging and fledging calls. Surprisingly, all cross-fostered chicks in our experiments were accepted by their foster parents, and male parents were as equally likely to accept cross-fostered chicks as females, even though the sexes would be expected to differ in offspring recognition due to different postfledging interactions with the chick. The revealed individuality of chick calls suggests the potential for chick vocal recognition in the studied species, but parent birds may disregard the individual characteristics enabling chick discrimination. This may take place as long as the chick is found in the nest because of the high likelihood that the chick present there is the focal one. However, IR during and after fledging requires further study. Studying the complexity of IR mechanisms is important for better understanding various avian social relationships and interactions.

The role of intergenerational support in shaping oral healthcare-seeking behavior among older adults in China.

This study aimed to explore how intergenerational support affects the oral healthcare or treatment-seeking behaviors of older Chinese adults and provide evidence for improving the oral health of the older adults in an aging society. Data from a cross-sectional survey, the 2015 China Health and Retirement Longitudinal Study, were used to explore the relationship between oral healthcare-seeking behavior in older adults and various independent variables, such as marital status, number of children, offspring's education duration, parent-offspring interaction frequency, and financial/material support provided by children. The chi-square test and binary logistic regression were used. According to the results of data analysis, age, sex, marital status, cohabitation status, number of children, children's education level, and financial support from children affected older adults' oral healthcare-seeking behavior. Interviewees living with a partner and those who had 1-2 or 3-4 children showed different likelihoods of seeking oral healthcare. Moreover, interviewees whose children had higher education duration and those who received more financial/material support from their children were more likely to seek dental treatment. Regarding the study's outcome, financial and emotional support, as well as practical assistance from family members can significantly promote oral health-seeking behavior among older adult people. Intergenerational support can serve as a crucial mechanism for promoting oral health behaviors among the older adults or act as a valuable complement to social medical assistance, warranting increased attention.

Cadmium does not affect post-hatching maternal care or early offspring development in earwigs

Abstract Anthropogenic pollution is steadily increasing and has a major impact on biodiversity. Chemical pollutants in particular affect many reproductive, physiological, and survival traits in a wide range of organisms. However, the effects on behavioral traits have been less studied, although they could have wide-ranging negative effects from the individual to the community level. Here, we attempted to fill this knowledge gap by investigating the effect of a common heavy metal pollutant, cadmium, on post-hatching maternal care and juvenile development in the European earwig Forficula auricularia. We fed 108 earwig families with five different cadmium concentrations (0, 12.5, 25, 50, and 100 mg.L−1), and measured ten parameters related to offspring care, non-care maternal behaviors, investment in maternal care and two parameters of offspring development (offspring weight gain and survival). Somewhat surprisingly, we found no effect of cadmium ingestion on any of the parameters measured, except for maternal self-grooming behavior. In particular, the ingestion of cadmium by group members did not result in an overall decrease in the expression of care by the contaminated mothers or in an overall higher level of care received by the contaminated offspring. By contrast, mothers fed the highest dose of cadmium showed an increase in self-grooming, probably due to the stress of toxic ingestion. Overall, our study raises questions about whether and how parent–offspring interactions can alter the negative effects of contaminated environments in social species.

Linking internalizing and externalizing problems to warmth and negativity in observed dyadic parent–offspring communication

AbstractObjectiveThis study examined the relative associations of mothers'/fathers' and offspring's internalizing and externalizing problems with parent‐to‐offspring and offspring‐to‐parent warmth and negativity.BackgroundPsychological conditions of family members may be related to intrafamilial social interactions. Particularly, internalizing and externalizing problems may affect the quality of parent–offspring communication.MethodIn this study, fathers (N = 94), mothers (N = 125) and their offspring (N = 224, age rangeoffspring = 7.5–65.5 years) from 137 nuclear families participated in a behavioral conflict interaction task during which expressed warmth and negativity were observed. Associations between parents' and offspring's psychological problems (of the past 6 months) and parent‐to‐offspring and offspring‐to‐parent communication were tested simultaneously using structural equation models separated for fathers and mothers. Based on prior findings in the study sample, our analyses were controlled for history of childhood abuse.ResultsOffspring's internalizing problems were related to less negativity toward their father, whereas offspring's externalizing problems were related to more negativity toward their father and to receiving less warmth from their mother. Father's externalizing problems were linked to more negativity toward offspring. No associations were found between maternal and paternal internalizing problems and dyadic parent–offspring interactions, nor for maternal externalizing problems.ConclusionFindings support that psychological conditions of one family member have an impact on their social interactions within the family.ImplicationsSupporting families with interventions to improve parent–offspring interactions and (early) treatment of externalizing problems is recommended.

Mutual mother-pup acoustic identification in Asian particolored bats.

In many vertebrates, vocal communication is crucial in parent-offspring interactions, and parents are often able to discriminate between the calls of their own and others' offspring. There are many reports on the unidirectional recognition of isolation calls of pups by maternal bats, but few studies on the ability of bat pups to recognize maternal acoustic signals. In this study, we investigated whether the echolocation pulses of female Asian particolored bats (Vespertilio sinensis) and isolation calls of pups differ statistically among individuals. We used two-choice playback experiments to test whether the mothers and pups of V.sinensis can recognize each other by acoustic signals. Both the echolocation pulses of mother bats and the isolation calls of pups contained sufficient individual characteristics. Playback experiments showed that mothers were able to recognize isolation calls of pups, and most pups greater than 12 days old were able to distinguish echolocation pulses of their own mother from those of other mothers. This is the first use of two-choice acoustic signal playback experiments to confirm that pups can recognize their mothers by echolocation calls. The results provide behavioral evidence for bidirectional recognition of acoustic signals between mothers and infants in frequency-modulated type bats.

Ecology and evolution of bird sounds

Birds are among nature's most social animals. They are renowned for their group migrations, their cooperative foraging, their communal roosting, their synchronous breeding aggregations, their precise parent-offspring interactions, their coordinated group defenses and their intricate territorial and courtship rituals. In these and other contexts, and indeed in most moments of their lives, birds' capacities to navigate complex social demands and relationships can tip the balance between health or sickness, between reproductive success or failure, between life or death. It is thus no surprise that birds have evolved sophisticated systems for mediating social interactions. Foremost among these are communication signals, most evident in birds as songs, calls, color patterns and postural displays. These and other communication signals can transmit information about a signalers' status, motivations and possible future actions, for sensory and cognitive processing by signal receivers. In general, signals provide benefits for both signal senders and receivers. Consider the bright spring plumage of a male wood warbler who has established a breeding territory. The male's plumage pattern benefits him by signaling his 'ownership' of his territory, which can help him attract potential mates and preempt conflict with potential rivals. His plumage pattern also benefits his intended audiences: it informs females about the signaler's potential as a mate, and it informs other males about the degree of threat they might face were they to attempt a territory take-over. Communication signals are, in essence, a glue that maintains the cohesion of bird societies, and a currency that mediates sophisticated relationships within.

Parent-offspring turn-taking dynamics influence parents’ song structure and elaboration in a singing primate

Parent-offspring interactions are essential to interpret animal social evolution and behavior, but their role in mediating acoustic communication in animals that interact vocally is still unclear. Increasing evidence shows that primate vocal communication is way more flexible than previously assumed, and research on this topic can provide further information on how the social environment shaped vocal plasticity during the evolution of the Primate order. Indris communicate through elaborated vocal emissions, usually termed songs. Songs are interactive vocal displays in which all members of the family group alternate their emissions, taking turns during chorusing events. We aimed to understand whether specific rules regulate the turn-taking of different group members and investigate the flexibility of indris’ vocal behavior when co-singing with their offspring. We found that social factors can influence the turn-taking organization in a chorus, as offspring were more likely to drop out from the parents’ duet than join in, and we speculate that overlap might signal competition by members of the same-sex. The duet between the reproductive pair was the most common type of singing organization, followed by a duet between mothers and sons and the triadic interaction between mother, father, and son. Interestingly, parents’ solo singing seems to stimulate offspring to vocalize, and we also found that mothers and fathers simplify, at least in part, song elaboration when chorusing with offspring. Our results indicate that indris can perform short-time adjustments to the number of co-emitters and their identity: our approach is advantageous in highlighting the multilevel influences on primate vocal flexibility. Moreover, it provides evidence that some aspects of our vocal plasticity were already present in the lemur lineage.

Observations on parental care of the Eurasian Spoonbill (Platalea leucorodia) during the post-fledging dispersal

Abstract The number of available publications on the post-fledging parental care of wading birds (herons, ibises, spoonbills, and storks) and many other bird species is limited. In this study, I summarised the available knowledge collated from the observations of the Eurasian Spoonbills (Platalea leucorodia) in Hungary. A part of the available data is based on observations of colour-ringed individuals. The latest feeding event of a young by its parent was observed at Lake Csaj on 5 October 2020. The youngsters were being fed by their parents for 43 days (observed maximum) during the post-fledging dispersal. However, I estimated that this behaviour could even last for as long as 53 days. The parents lead (care for) their yearlings for 51 days (observed maximum), again I estimated that it could potentially last for a longer period of 63 days. The estimated length of parental care and feeding period could be longer or a little bit shorter during the post-fledging dispersal because it was not possible to follow the life of the families exactly. During parental care (feeding and leading of chicks), the majority of the colour-ringed Spoonbills were observed 2–26 km to the natal colonies of yearlings and the breeding colonies of the adults. However, on some occasions, they were 111–145 km far from those colonies. During the post-fledging dispersal, Spoonbills care for their chicks for a longer time than the European breeding heron species. A possible reason could be that the bills of young Spoonbills are not appropriate for fishing effectively at the beginning of fledging because of their shorter length and their less efficient hydrodynamic effect during lateral sweeping. Another reason could be that Spoonbills are tactile foragers and need more time to learn fishing. Based on data of a juvenile followed by a GPS device, learning the migration route and stop-over sites from parents or experienced adults could be important for Spoonbills, otherwise, young migrating alone with no accomplished individuals may not find the optimal routes and the proper stop-over areas. In the case of Spoonbills, we still do not know exactly the features of parental care during the post-fledging dispersal and have even less data on it during the migration. Thus, I request potential observers along the Adriatic Flyway to record the observations of parent-offspring interactions (feeding by parents, begging) particularly the Hungarian colour-ringed adults and/or young individuals and send data to the author’s e-mail address.

Sex-specific parental care during postfledging in common ravens

Parents face a trade-off when allocating limited resources to reproduction and self-maintenance, and this can result in differential investment in individual offspring when rearing multiple offspring simultaneously. In birds with biparental care, it is not well understood how each parent allocates its resources to different chicks of the same brood. Theory suggests that parental investment depends on offspring quality and brood size, but empirical quantification of parent–offspring interactions during the postfledging stage is often difficult. We worked with captive common ravens, Corvus corax, a slightly dimorphic songbird with extended periods of biparental care, to investigate the effects of offspring sex, body mass, brood age and brood size on the feeding probability by both parents. We further investigated the influence of the same factors on offspring begging behaviour and affiliative interactions between parent and offspring. Mothers were more likely to feed and affiliate with their offspring than fathers. Fathers were more likely to feed and affiliate with sons than daughters, whereas mothers showed no preference. When more than one son was present, fathers were more likely to feed and affiliate with heavier sons than light sons. Brood size increased the begging probability of chicks, but decreased their probability of being fed. Our results suggest that biparental care in ravens is skewed towards the mother and that paternal care is selective. Selective paternal investment in the heaviest son may be adaptive in a system where heaviest males better compete for resources during dispersal.

Survey of neurotransmitter receptor gene expression into and out of parental care in the burying beetle Nicrophorus vespilloides.

Understanding the genetic influences of traits of nonmodel organisms is crucial to understanding how novel traits arise. Do new traits require new genes or are old genes repurposed? How predictable is this process? Here, we examine this question for gene expression influencing parenting behavior in a beetle, Nicrophorus vespilloides. Parental care, produced from many individual behaviors, should be influenced by changes of expression of multiple genes, and one suggestion is that the genes can be predicted based on knowledge of behavior expected to be precursors to parental care, such as aggression, resource defense, and mating on a resource. Thus, testing gene expression during parental care allows us to test expectations of this “precursor hypothesis” for multiple genes and traits. We tested for changes of the expression of serotonin, octopamine/tyramine, and dopamine receptors, as well as one glutamate receptor, predicting that these gene families would be differentially expressed during social interactions with offspring and associated resource defense. We found that serotonin receptors were strongly associated with social and aggression behavioral transitions. Octopamine receptors produced a complex picture of gene expression over a reproductive cycle. Dopamine was not associated with the behavioral transitions sampled here, while the glutamate receptor was most consistent with a behavioral change of resource defense/aggression. Our results generate new hypotheses, refine candidate lists for further studies, and inform the genetic mechanisms that are co‐opted during the evolution of parent–offspring interactions, a likely evolutionary path for many lineages that become fully social. The precursor hypothesis, while not perfect, does provide a starting point for identifying candidate genes.

Child maltreatment and parent-offspring interaction: A multigenerational extended family design.

In the current study, the associations between multiple types of child maltreatment (CM), parent-offspring interactions, and family cohesion were examined in an extended family study. A total of 366 parent-offspring pairs from 137 nuclear families participated. Parents (Mage = 52.8 years, age range: 26.6-88.4 years, 57% female) reported about perpetrated CM and offspring (Mage = 25.7 years, range: 7.5-65.5 years, 58% female) about experienced CM during their childhood. Parent-offspring interactions were observed during a conflict interaction task. Cohesion within the nuclear family was observed during a playful tower building task. Results showed that parents and offspring displayed more aversive behavior in parent-offspring dyads characterized by higher levels of child abuse, but not in dyads characterized by higher levels of child neglect. In addition, less dyadic affective similarity was observed in parent-offspring dyads characterized by higher levels of child neglect, whereas dyadic affective similarity was higher in dyads characterized by higher levels of child abuse. Findings imply that interventions focused on parent-offspring interactions with a somewhat different content for neglectful and abusive families may be efficacious for families in the child welfare system. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Brood sex ratio modulates the effects of extra food on parental effort and sibling competition in a sexually dimorphic raptor

Conflicts are inherent to family systems and may occur at three levels. First, each parent benefits if its mate takes the greater share of parental investment. Second, offspring try to manipulate their parents into devolving more resources than it is optimal for them. Third, siblings compete for resources. Food availability can affect the dynamics of each level of interaction. By means of a food supplementation experiment, we assessed how the initial availability of extra food during breeding affects later parental effort, sibling competition, and parent-offspring interactions in a small dimorphic raptor, the lesser kestrel (Falco naumanni). Being the larger sex, female nestlings are likely to have higher energy requirements. Female-biased broods had a higher rate of aggressive interactions and were fed more frequently in control nests. Food was not shared evenly among broodmates, and daughters tended to receive more feedings than sons. In young broods, parents controlled food allocation by entering the nest, whereas in older broods, offspring controlled food allocation by monopolizing the nest site entrance. Extra food induced male parents to reduce the rate of feedings delivered by entering the nest. Additionally, extra food improved nestling growth in male-biased broods, leading to an increase in the frequency of parental feedings and aggressive interactions, likely due to faster growth rates. These findings reveal a key effect of brood sex ratio in determining family interactions in a species with reverse sexual size dimorphism and suggest that all levels of conflict between family members should be considered simultaneously when investigating the evolution of parental care. Breeding poses energetic costs on parents, and environmental resources are usually limited. To successfully breed, parents coordinate their efforts and manage the allocation of resources to offspring, while offspring communicate their needs. Conflict can arise among family members: each parent benefits if the other takes on most of the workload, offspring ask for more care than what parents can provide, and siblings compete for food. Food availability affects these interaction levels separately, but they have rarely been integrated. By providing extra food to lesser kestrel (Falco naumanni) nests, we show that parental provisioning behaviour and sibling competition are simultaneously affected by initial resource availability during breeding. Although lesser kestrel nestlings show only moderate sex differences in body size (and therefore energy requirements), the effect of extra food on family interactions primarily depended on the sex ratio of the brood.

Parental favoritism in a wild bird population.

In most taxa with altricial young, offspring solicit food from their parents using a combination of visual and acoustic stimuli, but exactly what these young are communicating, and how selection shapes parental responses, remains unresolved. Theory posits that parents' interpretation and response to begging should vary with the likelihood of a return on their investment. We tested this in a wild population of prothonotary warblers (Protonotaria citrea), predicting that parents bias food non-randomly toward certain individuals within their broods depending on both the size and number of offspring. We observed parent-offspring interactions and detected strong dependence between brood size and nestling size in shaping parental responses to begging. Larger siblings were less likely to solicit food during feeding events than their smaller siblings, but they received a disproportionate share from parents in nests containing fewer-than-average young, whereas the smaller-than-average nestlings were disproportionately fed in broods containing a greater-than-average number of young. These findings suggest that parents respond to begging signals according to multiple social cues, favoring the stronger siblings with greater survival prospects when few copies of their genes are present, but overtly favoring runts to ensure whole-brood survival when capable of fledging more young. Future experimental studies may shed light on the contributions of parental decision-making and memory, how young nestlings learn in parent-offspring communication systems, and the adaptive significance of these behaviors.

Supplemental Material for Child Maltreatment and Parent–Offspring Interaction: A Multigenerational Extended Family Design

Supplemental Material for Child Maltreatment and Parent–Offspring Interaction: A Multigenerational Extended Family Design

Genes coordinating selfishness and altruism between parents and offspring

The social bond between parent and offspring balances selfishness and altruism. We investigated how genes control these behaviors in European earwigs, and found 1600 genes associated with parenting, and two genes coordinating selfishness and altruism. Our results suggest that internal reward and communication, encoded by these genes, help maintain parent-offspring interactions. - submission by Min Wu

Paternal Deprivation and Female Biparental Family Rearing Induce Dendritic and Synaptic Changes in Octodon degus: I. Medial Prefrontal Cortex.

In most mammalian species parent-offspring interactions during early life periods primarily comprise social contacts with the mother, whereas the role of males in parental care is one of the most overlooked and understudied topics. The present study addressed the hypothesis that the complete deprivation of paternal care delays or permanently retards synaptic connectivity in the brain, particularly in the medial prefrontal cortex (mPFC) of the offspring in a sex-specific manner. Another aim of this study was to address the question whether and in which way replacing the father with a female caregiver (in our experiments the “aunt”) can “buffer” the detrimental effects of paternal deprivation on neuronal development. The comparison of: (a) single mother rearing; (b) biparental rearing by father and mother; and (c) biparental rearing by two female caregivers revealed that: (i) paternal care represents a critical environmental factor for synaptic and dendritic development of pyramidal neurons in the vmPFC of their offspring; (ii) a second female caregiver (“aunt”) does not “buffer” the neuronal consequences of paternal deprivation; and that (iii) neuronal development in the vmPFC is differentially affected in male and female offspring in response to different family constellations.

Wild mice with different social network sizes vary in brain gene expression

BackgroundAppropriate social interactions influence animal fitness by impacting several processes, such as mating, territory defense, and offspring care. Many studies shedding light on the neurobiological underpinnings of social behavior have focused on nonapeptides (vasopressin, oxytocin, and homologues) and on sexual or parent-offspring interactions. Furthermore, animals have been studied under artificial laboratory conditions, where the consequences of behavioral responses may not be as critical as when expressed under natural environments, therefore obscuring certain physiological responses. We used automated recording of social interactions of wild house mice outside of the breeding season to detect individuals at both tails of a distribution of egocentric network sizes (characterized by number of different partners encountered per day). We then used RNA-seq to perform an unbiased assessment of neural differences in gene expression in the prefrontal cortex, the hippocampus and the hypothalamus between these mice with naturally occurring extreme differences in social network size.ResultsWe found that the neurogenomic pathways associated with having extreme social network sizes differed between the sexes. In females, hundreds of genes were differentially expressed between animals with small and large social network sizes, whereas in males very few were. In males, X-chromosome inactivation pathways in the prefrontal cortex were the ones that better differentiated animals with small from those with large social network sizes animals. In females, animals with small network size showed up-regulation of dopaminergic production and transport pathways in the hypothalamus. Additionally, in females, extracellular matrix deposition on hippocampal neurons was higher in individuals with small relative to large social network size.ConclusionsStudying neural substrates of natural variation in social behavior in traditional model organisms in their habitat can open new targets of research for understanding variation in social behavior in other taxa.

Effects of inbreeding on behavioural plasticity of parent-offspring interactions in a burying beetle.

Inbreeding depression is defined as a fitness decline in progeny resulting from mating between related individuals, the severity of which may vary across environmental conditions. Such inbreeding-by-environment interactions might reflect that inbred individuals have a lower capacity for adjusting their phenotype to match different environmental conditions better, as shown in prior studies on developmental plasticity. Behavioural plasticity is more flexible than developmental plasticity because it is reversible and relatively quick, but little is known about its sensitivity to inbreeding. Here, we investigate effects of inbreeding on behavioural plasticity in the context of parent-offspring interactions in the burying beetle Nicrophorus vespilloides. Larvae increase begging with the level of hunger, and parents increase their level of care when brood sizes increase. Here, we find that inbreeding increased behavioural plasticity in larvae: inbred larvaereduced their time spent associating with a parent in response to the length of food deprivation more than outbred larvae. However, inbreeding had no effect on the behavioural plasticity of offspring begging or any parental behaviour. Overall, our results show that inbreeding can increase behavioural plasticity. We suggest that inbreeding-by-environment interactions might arise when inbreeding is associated with too little or too much plasticity in response to changing environmental conditions.

Begging behavior as an honest signal of need and parent-offspring association during the postfledging dependency period.

Honest signaling mechanisms can function to appropriate care to hungry offspring and avoid misdirected care of unrelated offspring. Begging, the behavior by which offspring solicit food and parental care, may be an honest signaling mechanism for need, as well as association of parents and offspring. Roseate terns (Sterna dougallii) exhibit prolonged parental care during the postbreeding staging period, offering an ideal system in which to study begging as an honest signaling mechanism. We conducted focal sampling during two premigratory staging seasons (2014 and 2015) at Cape Cod National Seashore, Massachusetts, USA to determine whether postfledging tern begging behavior was an honest signal for need and parent–offspring association. Based on honest signaling theory, we expected begging behavior to be highest during times of high perceived need, and we expected to see a decrease in begging behavior as young terns became increasingly independent of the care‐giving parent. Also, we predicted that young terns would be more likely to beg at parents than nonparents. We found that young roseate terns begged at their parents more often than nonparents; however, they did not always beg at parents. Model predictions of begging probability showed a linear relationship between begging and time of day and date of season, such that begging increased with time of day and decreased with date of season, respectively. Our results provide evidence for honest parent–offspring interactions and are inconsistent with parent–offspring conflict theory but suggest that begging may play a complex role in postfledging parent–offspring interactions.OPEN RESEARCH BADGES This article has been awarded Open Data, Open materials Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.5281/zenodo.2656718.

Sibling competition in Blue Tits (Cyanistes caeruleus) is stronger in homozygous broods

Abstract Heterozygosity affects mate selection and can modulate interactions among family members and their fitness-related decisions. We studied whether nestling heterozygosity affected parent–offspring interactions and sib–sib competition in the Blue Tit (Cyanistes caeruleus) while controlling for the degree of relatedness among nestlings. Demanding environmental conditions might make the detection of heterozygosity-fitness correlations easier. Thus, we also investigated whether the decision rules of family members according to offspring heterozygosity were affected by brood size, as a proxy of the strength of sibling conflict. We found that chick individual heterozygosity was positively although weakly associated with individual body mass. Mean brood heterozygosity did not predict fledging success, but broods that fledged more chicks showed a higher number of less common alleles. Interestingly, fathers, but not mothers, favored heterozygous broods with many nestlings, that is, heterozygous broods with higher potential for sibling conflict. Moreover, the lower the mean brood heterozygosity the stronger the begging intensity when parents were absent, regardless of brood size. Finally, the degree of relatedness among nestlings was not associated with any behavioral parameter, supporting a more prominent role for heterozygosity in shaping intra-family interactions. Our findings suggest that offspring heterozygosity determines sex-specific rules of parental care and that genetic diversity is associated with lower sibling competition.