Adoptive Siblings Research Articles

COMPARISON OF DNA METHYLATION IN SALIVA, BUFFY COAT AND PBMC SAMPLES IN CATSLIFE

Abstract The design of the Colorado Adoption/Twin Study of Lifespan behavioral development and cognitive aging (CATSLife) allows for separation of genetic and environmental factors affecting health and cognitive aging. Currently, this sample is transitioning through midlife. One goal of this study is to identify epigenetic changes associated with aging, however methylation profiles differ across tissue types. Therefore, we describe here the analysis of DNA methylation in three CATSLife sample types: saliva, buffy coat, and peripheral blood mononuclear cells (PBMCs). Obtaining saliva is least invasive, although it may be less informative about brain and cognitive aging processes. In contrast, while buffy coats and PBMCs may be more informative, obtaining blood is more invasive. Buffy coats are less expensive to obtain than PBMCs, however they contain more cell types which may complicate analysis. Our analyses of 91 participants, suggested that saliva samples were less likely to pass initial quality control (< 96% CpGs detected). Unsurprisingly, the buffy coat and PBMC DNA methylation signatures are more similar to each other (r=0.97) than either is to saliva (rs=0.88—0.92). In initial analyses, each sample type demonstrated expected familial/heritable patterns of similarity across sites (MZ twins > DZ twins > biological & adoptive siblings). Given the additional cost of isolating PBMCs and computational methods to account for complex cell mixtures, the use of buffy coat DNA increases accessibility to analyze epigenetic changes longitudinally, enabling the early identification of epigenetic biomarkers of cognitive decline and the effect of both genes and environments on this process.

The Role of Communication in the Quality of Relationships for Biological Children in Adoptive Families

Recent literature reveals the multifaceted experiences of the biologically related children of parents in adoptive families, or adoptive siblings. Adoptive siblings report a range of positive and negative experiences related to adoption. Some adoptive siblings describe their families as fractured or broken after adoption while others describe adoption as bringing their families closer together. Because of the range of experiences expressed, the current study examines specific factors to determine what is related to or affects adoptive sibling’s view of their family relationships. Results of this study revealed that no specific family factors were significantly related to adoptive sibling’s views; however, adoptive siblings who reported being in families that talked openly and honestly about their thoughts and feelings reported increased family connection and satisfaction and increased sibling closeness with their adopted sibling. These findings elicit further understanding of the adoptive sibling experience and include clinical implications for supporting adoptive families post-adoption.

Familial resemblance, citizenship, and counterproductive work behavior: A combined twin, adoption, parent-offspring, and spouse approach.

Given the well-documented importance of counterproductive workplace behavior and organizational citizenship behavior (together nontask performance), it is important to clarify the degree to which these behaviors are attributable to organizational climate versus preexisting individual differences. Such clarification informs where these behaviors stem from, and consequently has practical implications for organizations (e.g., guiding prioritization of selection criteria). We investigated familial resemblance for nontask performance among twins, nontwin and adoptive siblings, parents and offspring, and midlife and late-life couples drawn from two, large-scale studies: the Minnesota Twin Family Study and the Sibling Interaction Behavior Study. Similarity among family members' (e.g., parents-offspring, siblings) engagement in nontask performance was assessed to estimate the degree to which preexisting individual differences (i.e., genetic variability) and the environment (i.e., environmentality) accounted for variation in counterproductive and citizenship behavior. We found that degree of familial resemblance for nontask performance increased with increasing genetic relationship. Nonetheless, genetically identical individuals correlated only moderately in their workplace behavior (r = .29-.40), highlighting the importance of environmental differences. Notably, family members were more similar in their counterproductive than citizenship behavior, suggesting citizenship behavior is comparatively more environmentally influenced. Spouse/partner similarity for nontask behavior was modest and did not vary between midlife and late-life couples, suggesting spousal influence on nontask performance is limited. These findings offer insight to organizations regarding the degree of nature (individual differences) and nurture (including organizational factors) influences on nontask performance, which has implications for the selection of interventions (e.g., relative value of applicant selection or incumbent interventions). (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Same-Sex Marriage and Common Mental Health Diagnoses: A Sibling Comparison and Adoption Approach

ABSTRACT We aimed to test whether the association between same-sex marriage and common mental health diagnoses was explained by shared genetic and environmental familial influences using sibling comparison and adoption analyses. For the sibling comparison analysis, participants (1,177,712 men and 1,266,917 women) were individuals born in Sweden between 1932 and 1994 and had ever been recorded as married (in opposite-sex or same-sex marriages). For the adoption analysis, participants were 147,164 and 1,298 female–female full sibling and adoptive sibling pairs, respectively. Based on medical records, prescribed medication, and death certificates, depression, substance abuse, and suicide (completed and attempted) from age 18 years were identified. For both sexes, being in a same-sex marriage was associated with greater risk of depression, substance abuse, and suicide, compared with being in an opposite-sex marriage. Controlling for shared familial confounding reduced this difference by less than 20% in magnitude, but overall mental health disparities for individuals in same-sex marriages remained statistically significant. Among women, only the genetic correlation between same-sex marriage and depression was statistically significant (r = .33). Same-sex marriage, as a proxy for sexual orientation, was associated with increased risk of certain mental health diagnoses and shared familial confounding explained a small component of this association, depending on the diagnosis. The findings indicate that sexual orientation disparities in mental health outcomes may involve unmeasured factors, and a relatively small proportion should be considered that may be due to shared familial confounding relevant to both sexual orientation and psychopathology.

Genetic associations between executive functions and intelligence: A combined twin and adoption study.

Much debate has concerned the separability of executive function abilities and intelligence, with some evidence that the 2 constructs are genetically indistinguishable in children and adolescents but phenotypically and genetically distinct in older adolescents and adults. The current study leveraged data from twin and adoption studies to examine executive function's genetic structure in adulthood (M = 33.15 years, SD = 4.96) and its overlap with intelligence. 1,238 individuals (170 MZ twin pairs, 154 DZ twin pairs, 95 biological sibling pairs, 80 adoptive sibling pairs, and 240 unpaired individuals) completed 6 executive function tasks as well as the Weschler Adult Intelligence Scale-III as part of the Colorado Adoption/Twin study of Life span behavioral development and cognitive aging (CATSLife). Results replicated the unity/diversity model of executive function that distinguishes general executive function abilities (Common EF) from abilities specific to working memory updating (Updating-specific) and mental set shifting (Shifting-specific). In the final model, broad-sense heritability was high for Common EF (h² = .72), Updating-specific (h² = 1.0), and Shifting-specific (h² = .60) factors, as well as for full-scale intelligence (h² = .74). Intelligence was phenotypically and genetically correlated with Common EF (r = .49, broad-sense rg = .44) and Updating-specific (r = .60, rg = .69) abilities. This study represents the first executive function study to apply the adoption design. Leveraging the combined twin and adoptive design allowed us to estimate both additive and nonadditive genetic effects underlying these associations. These findings highlight the commonality and separability of executive function and intelligence. Common EF abilities are distinct from intelligence in adulthood, with intelligence also strongly associated with Updating-specific abilities. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

An Exploratory Study of the Impact of Adoption on Adoptive Siblings

There is extensive literature on the effects of early-life trauma in children who are adopted, but limited research on the effects this early-life trauma may have on the other members of the adoptive family system. This qualitative study explored the experience of adoptive siblings, defined as biological children in families who adopt children, and the impact adoption has had on them. A sample of 182 adult adoptive siblings, aged 18–64 years, were surveyed retrospectively about their experience in their families from pre-adoption to post-adoption. Through phenomenological qualitative analysis, responses were categorized based on pre-adoption, the initial adoption transition, and post-adoption. Results of this study indicated that adoptive siblings often felt invisible or resentful. Many adoptive siblings experienced parentification or took on the role of peacemaker in their families. The results also revealed that the impact of adoption for adoptive siblings can lead to personal growth, including empathy, compassion, and maturity, or mental health issues, including an inability to trust others, a jaded worldview, and posttraumatic symptoms. Further, many adoptive siblings decided to foster or adopt as adults or enter the child welfare profession. These results suggest that adoptive siblings are impacted by the experience of adoption in their families, and further, this may lead to long-term effects on their lives. Further research is needed to better understand what factors may be related to more positive or negative experiences with adoption, which could allow for a greater understanding of how to support this population from pre- to post-adoption.

An Infant with Worsening Rash.

A 3-month-old boy presented with 2 weeks of a worsening rash that started around his mouth. His mother suspected irritation from his pacifier, but the rash continued to spread, prompting a visit to an urgent care center. He was diagnosed with impetigo, and he received oral amoxicillin and topical mupirocin to little effect. He had been afebrile from the start, without any symptoms of upper respiratory infection, respiratory distress, hair loss, vomiting, or diarrhea. He breast-fed well from his adoptive mother since shortly after birth (she was nursing 1 of her biological children at the same time), and the mother had no dietary restrictions. There were no similar rashes in his adoptive siblings. After failing to respond to antibiotic therapy, the boy was sent to a dermatologist, who performed a punch biopsy. When the pathology results became available, the patient's family was directed to bring him to the emergency department. As depicted in Fig. 1, the physical examination revealed numerous erythematous and heme-crusted plaques with “flaky paint” scale on …

I [Don’t] Belong Here: Narrating Inclusion at the Exclusion of Others

Borrowing from narrative research and Disability Studies in Education, Emily tells the story of her adoptive siblings Maria and Isaac, who were orphaned by AIDS. She explores the paradox of inclusion which is that it sometimes, if not oftentimes, fails and results in exclusion. A chief reason for the failure of inclusion, Emily argues, is that children with real and perceived differences challenge the “grammar” of schooling—that is, they stand out for their differences.

The role of siblings in adoption outcomes and experiences from adolescence to emerging adulthood.

In many families, siblings play important roles in shaping each other's outcomes and experiences across development. In adoptive families, siblings may affect adoptees' feelings about adoption and birth family contact. Among "target adoptees" (i.e., 1 participating adopted individual within adoptive families) with siblings who may have also been adopted or the biological children of the adoptive parents, we examined how adoption experiences and individual adjustment from adolescence into emerging adulthood were associated with sibling relationship dynamics. We present 3 studies using longitudinal, mixed method data within the same overarching sample of adoptive families. Study 1 was a follow-up to Berge et al.'s (2006) study of adolescent adoptees and their adopted siblings with birth family contact; we found evidence of changes in the status of contact collectively experienced by 26 adopted sibling pairs when target adoptees were emerging adults. In Study 2, we found that target adoptees (n = 91) with siblings (adopted or not) who were more involved with target adoptees' birth family contact demonstrated more favorable behavioral outcomes than target adoptees who had uninvolved siblings. Finally in Study 3, for target adoptees with siblings who were also adopted (n = 51), results showed that target adoptees felt more positively about their own adoption when siblings expressed similar positive feelings about individual adoption experiences. Implications of our findings are discussed in terms of the enduring contributions of sibling relationships from childhood into adulthood and the unique ways in which adoptive siblings are important in shaping one another's experiences of adoption.

Is self-regulation “All in the family”? Testing environmental effects using within-family quasi-experiments

Most of the individual difference variance in the population is found within families, yet studying the processes causing this variation is difficult due to confounds between genetic and nongenetic influences. Quasi-experiments can be used to test hypotheses regarding environment exposure (e.g., timing, duration) while controlling for genetic confounds. To illustrate, two studies of cognitive self-regulation in childhood (i.e., working memory, effortful control, attention span/persistence) are presented. Study 1 utilized an identical twin differences design (N = 85-98 pairs) to control for genetic differences while using relative twin birth weight difference to predict relative twin difference in working memory and effortful control. Larger relative twin difference in working memory and effortful control was predicted by the combination of shorter gestation and larger relative birth weight difference. Study 2 utilized an adoptive sibling relative difference design (N = 123 same-sex pairs) to control for genetic similarity while using relative sibling difference in age at time of adoption to predict relative sibling difference in attention span/persistence. Larger relative sibling difference in attention span/persistence was predicted by the combination of larger relative difference in time in the adoptive home and age at adoption. Within-family quasi-experimental designs allow stronger inferences about hypothesized environmental influences than between-family designs permit.

Do parents favor their adoptive or biological children? Predictions from kin selection and compensatory models

Evolutionary reasoning (Kin Selection Theory) predicts less favorable behaviors directed by parents toward their unrelated children, relative to their biologically related children. By extension, it may be argued that parents should also have less favorable perceptions of the intellectual, personality and other behavioral traits of unrelated children, compared with biologically related children. However, recent work has modified this expectation, given the distinction between unrelated adopted children (who are acquired intentionally) and unrelated stepchildren (who are acquired via mating effort). The compensatory model takes into account evolved desires for parenting and the evolutionarily novel availability of unrelated children. It predicts that adopted children may be viewed as favorably, or even more favorably, than biological children due to parents' compensation for the perceived challenges and stigma linked to their exceptional family structure. In the present study, IQ, Adjective Checklist and Child Behavior Checklist scale scores were available for 135 virtual twin pairs (same-age unrelated siblings raised together). Virtual twins included 41 adopted–biological pairs and 94 adopted–adopted pairs, with a mean age of 6.14years (SD=3.51). These unique data allowed tests of hypotheses and predictions concerning parenting perceptions, given the matched age and placement of the biological and adoptive siblings. Consistent with prior research, the IQ scores of the biological children exceeded those of the adopted children, both between and within pairs. A between-pair analysis revealed no difference between biological children and members of adopted–adopted pairs in ratings of favorable or unfavorable traits. However, more telling within-family comparisons of adopted–biological pairs revealed higher scores for adoptees on unfavorable traits, consistent with Kin Selection Theory, but no differences between adoptive and biological children on favorable traits, consistent with the compensatory model. These findings refine our understanding of parenting genetically related and unrelated offspring.

Replication of a Gene–Environment Interaction Via Multimodel Inference: Additive-Genetic Variance in Adolescents’ General Cognitive Ability Increases with Family-of-Origin Socioeconomic Status

The present study of general cognitive ability attempts to replicate and extend previous investigations of a biometric moderator, family-of-origin socioeconomic status (SES), in a sample of 2,494 pairs of adolescent twins, non-twin biological siblings, and adoptive siblings assessed with individually administered IQ tests. We hypothesized that SES would covary positively with additive-genetic variance and negatively with shared-environmental variance. Important potential confounds unaddressed in some past studies, such as twin-specific effects, assortative mating, and differential heritability by trait level, were found to be negligible. In our main analysis, we compared models by their sample-size corrected AIC, and base our statistical inference on model-averaged point estimates and standard errors. Additive-genetic variance increased with SES-an effect that was statistically significant and robust to model specification. We found no evidence that SES moderated shared-environmental influence. We attempt to explain the inconsistent replication record of these effects, and provide suggestions for future research.

Child's needs key to sibling adoption

When placing siblings for adoption, social workers must no longer assume they should be kept together

Continuity of genetic and environmental influences on cognition across the life span: a meta-analysis of longitudinal twin and adoption studies.

The longitudinal rank-order stability of cognitive ability increases dramatically over the life span. Theoretical perspectives differ in their emphasis on genetic mechanisms in explaining the longitudinal stability of cognition and how stability changes with development. However, the patterns of stability of genetic and environmental influences on cognition over the life span remain poorly understood. We searched for longitudinal studies of cognition that reported raw genetically informative longitudinal correlations or parameter estimates from longitudinal behavior genetic models. We identified 150 combinations of time points and measures from 15 independent longitudinal samples. In total, longitudinal data came from 4,548 monozygotic twin pairs raised together, 7,777 dizygotic twin pairs raised together, 34 monozygotic twin pairs raised apart, 78 dizygotic twin pairs raised apart, 141 adoptive sibling pairs, and 143 nonadoptive sibling pairs, ranging in age from infancy through late adulthood. At all ages, cross-time genetic correlations and shared environmental correlations were substantially larger than cross-time nonshared environmental correlations. Cross-time correlations for genetic and shared environmental components were, respectively, low and moderate during early childhood, increased sharply over child development, and remained high from adolescence through late adulthood. Cross-time correlations for nonshared environmental components were low across childhood and gradually increased to moderate magnitudes in adulthood. Increasing phenotypic stability over child development was almost entirely mediated by genetic factors. Time-based decay of genetic and shared environmental stability was more pronounced earlier in child development. Results are interpreted in reference to theories of gene-environment correlation and interaction.

Genetic and familial environmental effects on suicide attempts: A study of Danish adoptees and their biological and adoptive siblings

ObjectivesGenetic factors have been found to influence the risk of suicide. It is less clear if this also applies to attempted suicide. We have investigated genetic and familial environmental factors by studying the occurrence of suicide attempts in biological and adoptive siblings of adoptees who attempted suicide compared to siblings of adoptees with no suicide attempts. MethodWe used a random sample of 1933 adoptees from the Danish Adoption Register, a register of non-familial adoptions of Danish children, i.e. the adoptive parents are biologically unrelated to the adoptee. Analyses were conducted on incidence rates of attempted suicide in biological and adoptive siblings given occurrence of attempted suicide in the adoptees while also taking into account psychiatric disorders. Information about suicidal attempt and history of psychiatric disorder was based on hospital admissions. ResultsThe rate of attempted suicide in full siblings of adoptees who attempted suicide before age 60 years was higher than in full siblings of adoptees who had not attempted suicide (incidence rate ratios (IRR)=3.45; 95% confidence interval [CI]=0.94–12.7). After adjustment for history of psychiatric admission of siblings the increased rate was statistically significant (IRR=3.88; 95% CI—1.42–10.6). LimitationsInformation on attempted suicide and psychiatric history was limited to that which involved hospitalisation. ConclusionsGenetic factors influence risk of suicide attempts.

Genetic and familial environmental effects on suicide--an adoption study of siblings.

BackgroundWhile there is clear evidence of familial influences on suicide, the origin of these is less certain. We have investigated genetic and familial environmental factors by studying the occurrence of suicide in biological and adoptive siblings of adoptees who died by suicide compared to siblings of surviving adoptees.MethodWe used the Danish Adoption Register and Danish population registers to compare 221 siblings of adoptees who died by suicide with the siblings of 1,903 adoptees who did not die by suicide. All adoptions in the Danish Adoption Register are non-familial, i.e. the adoptive parents are biologically unrelated to the adoptee. Analyses were conducted on incidence rates of suicide in biological and adoptive siblings given occurrence of suicide in the adoptees while also taking into account psychiatric disorders.ResultsThe risk of suicide in full siblings of adoptees who died by suicide before age 60 years was significantly higher than in full siblings of adoptees who had not died by suicide (incidence rate ratios (IRR) = 5.01; 95% confidence interval [CI] = 1.28 - 19.6). This increase persisted after adjustment for history of psychiatric admission of siblings (IRR = 4.19; 95% CI = 1.00 - 17.5).ConclusionsGenetic factors influence risk of suicide, probably independently of psychiatric disorder. This is relevant in provision of advice to families, including possible prevention of suicide.

Genetic and Environmental Influences on the Familial Transmission of Externalizing Disorders in Adoptive and Twin Offspring

Twin-family studies have shown that parent-child resemblance on substance use disorders and antisocial behavior can be accounted for by the transmission of a general liability to a spectrum of externalizing disorders. Most studies, however, include only biological parents and offspring, which confound genetic and environmental transmission effects. To examine the familial transmission of externalizing disorders among both adoptive (genetically unrelated) and biological relatives to better distinguish genetic and environmental mechanisms of transmission. Family study design wherein each family included the mother, father, and 2 offspring, including monozygotic twin, dizygotic twin, nontwin biological, and adoptive offspring. Structural equation modeling was used to estimate familial transmission effects and their genetic and environmental influences. Participants were recruited from the community and assessed at a university laboratory. A total of 1590 families with biological offspring and 409 families with adoptive offspring. Offspring participants were young adults (mean age, 26.2 years). Symptom counts of conduct disorder, adult antisocial behavior, and alcohol, nicotine, and drug dependence. RESULTS There was a medium effect for the transmission of the general externalizing liability for biological parents (r = 0.27-0.30) but not for adoptive parents (r = 0.03-0.07). In contrast, adoptive siblings exhibited significant similarity on the general externalizing liability (r = 0.21). Biometric analyses revealed that the general externalizing liability was highly heritable (a2 = 0.61) but also exhibited significant shared environmental influences (c2 = 0.20). Parent-child resemblance for substance use disorders and antisocial behavior is primarily due to the genetic transmission of a general liability to a spectrum of externalizing disorders. Including adoptive siblings revealed a greater role of shared environmental influences on the general externalizing liability than previously detected in twin studies and indicates that sibling rather than parent-child similarity indexes important environmental risk factors for externalizing disorders.

The Nature and Nurture of High IQ

IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a cross-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings.

Perceived relationship quality in adolescents following early social-emotional deprivation

Children who spend their early life in social-emotionally depriving institutions have limited opportunities to engage in relationships. This early experience has been associated with many problematic behavioral outcomes; however, researchers have not frequently examined relationship quality of post-institutional adoptees, nor have they examined aspects of the adoptive family that might moderate institutionalization effects. The purpose of this study was to examine the self-reported relationship quality of 10-17-year-old children adopted into the USA from Russian institutions and to determine whether sibling characteristics (relative age, gender composition, sibling adoption status) moderate institutionalization effects. Older age at adoption was related to poorer friendship and sibling, but not mother, relationship quality. Older siblings and same-sex siblings buffered children from this negative age-at-adoption association.

Peer Deviance, Alcohol Expectancies, and Adolescent Alcohol Use: Explaining Shared and Nonshared Environmental Effects Using an Adoptive Sibling Pair Design

Previous research suggests adolescent alcohol use is largely influenced by environmental factors, yet little is known about the specific nature of this influence. We hypothesized that peer deviance and alcohol expectancies would be sources of environmental influence because both have been consistently and strongly correlated with adolescent alcohol use. The sample included 206 genetically related and 407 genetically unrelated sibling pairs assessed in mid-to-late adolescence. The heritability of adolescent alcohol use (e.g., frequency, quantity last 12months) was minimal and not significantly different from zero. The associations among peer deviance, alcohol expectancies, and alcohol use were primarily due to shared environmental factors. Of special note, alcohol expectancies also significantly explained nonshared environmental influence on alcohol use. This study is one of few that have identified specific environmental variants of adolescent alcohol use while controlling for genetic influence.