Prenatal Testosterone Exposure Research Articles

The association between 2D:4D digit ratio and sex-typed play in children with and without siblings

The 2D:4D digit ratio is commonly used as a surrogate possibly reflecting prenatal testosterone levels. Indirect evidence comes from studies investigating the association between 2D:4D and human characteristics that likely relate to prenatal testosterone. In children, sex-typed play reveals large sex differences early in development and an influence of prenatal testosterone is likely. Findings on the association between 2D:4D and children’s sex-typed play are heterogeneous and other influences on the development of sex-typed play have been suggested, most of all social influences like siblings, their sex and birth order. The current study examined the association between right and left 2D:4D, a proposed surrogate for prenatal testosterone exposure, which was assessed in right and left hands of N = 505 6-month-old children, and sex-typed play behavior, which was evaluated 3.5 years later using the Pre-School Activities Inventory (PSAI), and the influence of siblings. To capture differential effects of siblings’ sex and birth order, dummy-coded variables were used reflecting having no siblings as well as older or younger sisters or brothers. Multiple regression models were used to investigate the association between PSAI scores and sex, right and left 2D:4D, being a singleton as well as having an older or younger sister or brother. It was shown that sex and having an older brother were significant predictors for sex-typed play. Effects were further disentangled by conducting separate regression analyses in boys and girls. In boys, a significant association between PSAI scores and having an older brother was revealed, in girls, no significant associations were found. Results are discussed highlighting the non-significant association between 2D:4D and children’s sex-typed play, which weakens the applicability of 2D:4D as a surrogate reflecting influences of prenatal T. Further, the importance of social factors like siblings on children’s sex-typed play is discussed.

Prenatal testosterone exposure and offspring body composition at 7 years-of-age. odense child cohort

Prenatal testosterone exposure and offspring body composition at 7 years-of-age. odense child cohort

The change in handgrip strength, after physical exercise, is moderated by digit ratio (2D:4D): A study among the young adults in Poland.

The digit ratio (2D:4D), the ratio of the lengths of second (2D) to the fourth (4D) fingers, is a proxy indicator of prenatal androgen exposure. On average, males display lower 2D:4D than females. Previous studies have shown that lower 2D:4D ratios were associated with better sports and physical abilities. To assess whether a challenge condition, imposed by intense exercise, could increase handgrip strength (HGS) associated with 2D:4D. This cross-sectional experimental study included 90 healthy young Polish adults (40 males, 50 females). They underwent intense physical exercise, before (7 days) and after which they were measured for HGS and 2D:4D. Height and weight were also measured. Analyses of Covariance were employed to delineate associations. 2D:4D had significant predictive effects on the differences in HGS (DHGS) measured in two occasions, without and after, physical exercises. The lower was the 2D:4D, the higher the DHGS, particularly, for the left hand. The results reconfirmed that the link between prenatal testosterone exposure (indicated by 2D:4D) and physical strength depends on the context, such as a challenged condition.

Exploring Hematological and Biochemical Disparities in Same-Sex and Opposite-Sex Females: A Cross-Sectional Twin Study in a Ghanaian Population.

There are sex-dependent differences in hematological and biochemical variables in adulthood attributed to the predominant effects of testosterone in males and estrogen in females. The Twin Testosterone Transfer (TTT) hypothesis proposes that opposite-sex females may develop male-typical traits due to exposure to relatively higher levels of prenatal testosterone than same-sex females. Additionally, prenatal testosterone exposure has been suggested as a correlate of current circulating testosterone levels. Consequently, opposite-sex females might exhibit male-typical patterns in their hematological and biochemical variables. Despite this hypothesis, routine laboratory investigations assign the same reference range to all females. Our cross-sectional study, conducted in Tamale from January to September 2022, included 40 twins, comprising 10 opposite-sex (OS) males (25%), 10 OS females (25%), and 20 same-sex (SS) females (50%), all aged between 18 and 27 years. Fasting venous blood samples were collected and analyzed using automated hematology and biochemistry laboratory analyzers. Results indicated that levels of hemoglobin, serum creatinine, gamma-glutamyl transferase, total protein, globulins, and total testosterone were significantly higher in OS males than OS females. Conversely, total cholesterol and low-density lipoprotein cholesterol were significantly higher in OS females than OS males. Unexpectedly, levels of low-density lipoprotein cholesterol and total testosterone were significantly higher in SS females than OS females. Contrary to expectations, opposite-sex females did not exhibit male-typical patterns in their hematological and biochemical variables. This suggests that the TTT effect may not occur or may not be strong enough to markedly affect hematological and biochemical variables in OS females.

2D:4D ratio, alexithymia, impulsivity, aggression, and ADHD in men with opioid and methamphetamine use disorders: A comparative analysis with healthy controls

Substance use disorder is an important mental health problem with increasing frequency. This study aims to investigate the 2D:4D ratio, Dr-I values (right-left differences), alexithymia, aggression, impulsivity, and attention deficit hyperactivity disorder (ADHD) symptoms in male patients with methamphetamine use disorder (MUD), opioid use disorder (OUD), and healthy controls. The study included a total of 57 male patients diagnosed with OUD, 42 male patients diagnosed with MUD, and 72 healthy male controls. The study indicated that the OUD and MUD patients were significantly different from the healthy controls in terms of the 2D:4D ratio, alexithymia, impulsivity, aggression, and ADHD. Compared to healthy controls, 2D:4D ratios, and Dr-I values were lower in OUD and MUD patients. OUD and MUD patients had higher scores of alexithymia, impulsivity, aggression, and ADHD compared to healthy controls. There were statistically significant negative correlations between the right-hand 2D:4D ratios and the ADHD, impulsivity, alexithymia and aggression scores and a significant negative correlation between Dr-I scores and the impulsivity scores of MUD and OUD patients. These findings contribute to the existing literature examining the complex relationship between prenatal testosterone exposure, substance use disorders and related psychological traits.

Prenatal Exposure to Androgens and Gender Socialisation Effects on Children’s Academic Interests

AbstractPrevious studies have documented gender differences in fields of study as well as interest in school subjects. Boys are on average more interested in mathematics, and girls show greater interest in languages. The extent to which these disparities are the result of biological or environment influences is still an open debate. On the one hand, brain organisation theory suggests that physiological and behavioural differences may be linked to prenatal hormone levels. On the other hand, sociological and psychological perspectives highlight the importance of gender socialisation. This paper combines biological, psychological, and sociological perspectives to examine the emergence of gendered academic interests in children.The study draws on data from 9‑year-old children from the Avon Longitudinal Study of Parents and Children (ALSPAC). Our results suggest that for both boys and girls, medium to high compared with low prenatal exposure to circulating maternal testosterone might increase children’s interests in mathematics relative to English, although results vary depending on how prenatal testosterone exposure is measured. As the distributions of prenatal androgen exposure and the relationships with maths versus English interests are very similar for boys and girls, prenatal androgen exposure does not contribute to explaining gender differences in academic interests. However, we find some evidence that the relationship with parental gender socialisation varies by prenatal androgen exposure. A more gender-equal parental division of domestic work is more strongly associated with less gendered academic interests for girls with low prenatal androgen exposure and for boys with medium to high androgen exposure.

Is prenatal testosterone-estrogen balance related to critical shoulder angle?

BackgroundThe 2D:4D ratio (an indicator of prenatal testosterone-estrogen balance) is the ratio of the second finger length to the fourth finger length. We hypothesized that low 2D:4D values indicating high prenatal testosterone exposure may be associated with increased critical shoulder angle (CSA). AimsThe aim of this study was to evaluate the relationship between CSA and 2D:4D ratio. MethodsMeeting the study criteria, 252 patients were included in the study. We measured CSA on true anterior-posterior radiographs, glenoid version(GV) and glenoid inclination(GI) on MRI images and the lengths of the second and fourth fingers on both hands of the patients. Additionally, we compared 2D:4D ratios and CSA, GV, GI measurements. ResultsWe found a significant negative correlation between CSA and the 2D:4D ratio in both hands (p < 0.001). Patients with CSA > 35° had a significantly lower 2D:4D ratio than patients with CSA < 35° (p < 0.001). When the patients were grouped according to CSA35°, the cut-off value for the left-hand 2D:4D ratio was 0.96, which showed 84.8 % sensitivity and 83.3 % specificity(AUC:0.911). Patients were compared in terms of CSA by categorizing as 2D:4D > 1 and 2D:4D < 1. Accordingly, the CSA value was significantly lower in patients with 2D:4D > 1. In the classification made according to this length classification of the left hand, the cut-off value was 30.25°. This value showed 92.2 % sensitivity and 85 % specificity(AUC:0.956). ConclusionThe 2D:4D ratio is related to CSA. A low 2D:4D ratio(<0.96), indicating high intrauterine testosterone exposure, is associated with CSA > 35°, while a high 2D:4D ratio (>1), indicating low intrauterine testosterone exposure, is associated with a low CSA(<30.25°).

The associations between 2D:4D ratio and behavior problems among Chinese preschool children: A cross-sectional study

BackgroundDigit ratio (2D:4D) is considered a biomarker of prenatal androgen activity, the prenatal hormone exposure may affect children's psychology and behavior. ObjectiveThe aim of this study was to analyze the associations between 2D:4D ratio and behavior problems in Chinese preschool children, and to provide ideas for early intervention of children's behavior problems. MethodsA total of 548 Chinese preschool children aged 3–6 years were recruited using a stratified cluster sampling method. The Child Behavior Checklist (CBCL) was used to assess the children's behavior. Basic information of the children and their parents was also collected, finger length was directly measured by electronic vernier caliper. ResultsWe found that sex and age of the child, mother's educational level, and whether the child was an only child were the influencing factors of behavior problems (P < 0.05). Right-handed 2D:4D was negatively correlated with parent-reported anxiety/depression (P < 0.05), father-reported aggression (P < 0.05) and attention problems (P < 0.01), that is, high levels of testosterone may increase the risk of anxiety and depression, our results were in contrast to previous studies. ConclusionThe 2D:4D ratio may be related to behavior problems among Chinese preschool children, and prenatal testosterone exposure may be an important factor affecting behavior problems.

Lower digit length ratio and aggression in adolescents and young adults with boxer's fracture: A case-control study.

Recent evidence shows that a lower second-to-fourth digit ratio (2D:4D), which is a sexually dimorphic trait and the indicator of prenatal testosterone exposure, may be associated with aggressive behaviors. In this cross-sectional, case-control study, we investigated: (1) Are the aggression and impulsivity levels and emotional problems higher? (2) Is the 2D:4D ratio lower in adolescents and young adults who presented with a fifth metacarpal neck fracture (boxer's fracture) compared to controls? (3) Is the digit ratio correlated with aggressive measures in individuals with a fifth metacarpal neck fracture?Seventy-one consecutive patients presented with a fifth metacarpal neck fracture within the age range of 11-25 years old comprised the study group. The control group consisted of 71 age and sex-matched subjects without a history of aggression-related injury. The aggression, impulsiveness, and psychosocial well-being were measured by self-reported questionnaires. 2D:4D was measured by conventional radiography. The 2D:4D ratio was similar between groups, however, when the analyses were conducted separately for sex, females in the study group showed lower 2D:4D than females in the control group (p = 0.001). The aggression level of the study group, measured by the Buss-Perry Aggression Questionnaire was higher than the control group (p = 0.014). The impulsiveness scores on the BarrattImpulsiveness Scale-11were similar (p = 0.60) and the total difficulty score on the Strengths and Difficulties Questionnaire was higher in the study group (p = 0.009).A lower 2D:4D ratio significantly predicted verbal and total aggression scores (p = 0.036, p = 0.032, respectively). Our findings suggest that females with a history of aggression-related injury have lower 2D:4D, and a lower 2D:4D is correlated with higher aggression levels in both sexes. Understanding and addressing aggression in these patients may help prevent further self-inflicted injuries.

Systematical assessment of digit ratio in a female masculinization disease: polycystic ovary syndrome.

In recent years, the right ratio of 2nd and 4th digit length (2D:4D) is regarded as an anatomical marker of prenatal testosterone exposure. Polycystic ovary syndrome (PCOS) is a female masculinized disease and is determined by prenatal testosterone exposure. Whether the ratio in the right hand of PCOS women is reduced or not compared with non-PCOS women is under debate. To further investigate the relationship between PCOS and digit ratio, we systematically measured all the digit ratios. We recruited 34 non-PCOS women, 116 PCOS women, and 40 men and systematically measured all the ratios of digit length (2D:3D, 2D:4D, 2D:5D, 3D:4D, 3D:5D, and 4D:5D) of right hands and left hands. Left 2D:3D, 2D:4D, and 2D:5D in men were significantly lower than those in non-PCOS women. Significantly lower digit ratios of left 2D:3D and 2D:4D were observed in PCOS compared with non-PCOS women. In the subgroup analysis, the left ratio of digit length in 2D:3D and 2D:5D of the hyperandrogenism subgroup was lower than that of the non-hyperandrogenism subgroup without statistical significance. The logistic regression model of PCOS revealed that 2D:3D, 2D:4D, 2D:5D, and 3D:4D of left hands were statistically related to the diagnosis of PCOS among all the digit ratios. Not only 2D:4D but also other digit ratios, such as 2D:3D and 2D:5D, are a marker of prenatal testosterone exposure and may be an anatomical marker of PCOS. The majority of these significant differences included left 2D, with the following order: non-PCOS women > PCOS women > men.

Early prenatal sex steroids and sex-typed play behavior at 4 years of age

During pregnancy, estrogens and testosterone influence brain development, resulting in sex-typical behavioral phenotypes. Prenatal testosterone exposure is associated with more male-typical behaviors in rodents, monkeys, and humans; however, few studies have examined the relationship between maternal sex hormones within the normal range and sex-dimorphic behaviors. In this study, we examined associations between prenatal estrogens and testosterone and sex-typical play in The Infant Development and the Environment Study (TIDES), a multicenter pregnancy cohort. We collected prenatal serum during the first trimester (mean=11.1 ± 2.6 weeks) and assessed child play behavior using the maternally completed Pre-School Activities Inventory (PSAI) at a mean age of 4.5 ± 0.3 years. This analysis includes mother-child pairs with complete data on hormones, play behavior, and covariates (n = 192 boys and 207 girls). No associations were seen between testosterone and PSAI scores in boys or girls or between estrogens and PSAI scores in boys. In girls, we observed an inverse relationship between feminine PSAI scores and both estradiol (E2) and estriol (E3) in multivariable linear regression analyses (E2: −0.11 [95% CI −0.20, −0.02]; E3: −0.44 [95% CI −0.83,−0.04]). Because the relationship between sex hormones and PSAI scores appeared nonlinear, we fit piecewise regression models to better fit the data and identify inflection points (point at which there is a significant change in slope). Piecewise regression analyses yielded inverse associations between masculine PSAI scores and estrone (E1) at values of E1 > 1340 pg/mL and E2 at values of E2 > 2870 pg/mL in girls. Further studies are needed to better understand the role of prenatal sex steroids on sexually dimorphic behavior.

Dark Triad personality traits, second-to-forth digit ratio (2D:4D) and circulating testosterone and cortisol levels

IntroductionDark Triad (DT) personality traits (psychopathy, Machiavellianism, and narcissism) show sex differences and associations with hormones. Understanding aetiology may assist in mitigating the harm of these potentially adverse characteristics. Low second-to-fourth digit ratio (2D:4D) is hypothesised to be a marker of high prenatal testosterone exposure and may provide important information about organisational hormones. The aim of the present study was to measure Dark Triad and Big 5 personality traits in relation to digit ratio, salivary testosterone, and cortisol. MethodsA non-clinical sample (N = 268; 49.25% Female, age M25.20 ± 8.77 yrs) completed the Short Dark Triad and International Personality Inventory Pool - Mini. Afternoon saliva was analysed for testosterone and cortisol, and 2D:4D finger ratios were measured. ResultsMales scored higher on DT traits than females. Females scored higher on Big 5 agreeableness and neuroticism. Males had higher testosterone and cortisol levels and lower 2D:4D than females. Digit ratio correlated inversely with salivary testosterone, Machiavellianism, and psychopathy. Testosterone levels correlated positively with cortisol levels and psychopathy and negatively with agreeableness, neuroticism, and Machiavellianism. ConclusionsThese results provide indications that Machiavellianism and psychopathy (Dark Triad) traits, but not narcissism or Big 5 traits, are linked to markers of prenatal testosterone exposure. Results also replicate sex differences seen in 2D:4D digit ratios, with males having a shorter second-relative-to-forth finger. Links between circulating testosterone, digit ratios, cortisol and personality traits provide further information about potential biological bases of personality.

Cognitive reflection and 2D:4D: Evidence from a large population sample

Bosch-Domènech et al. (2014) reported a negative association between 2D:4D, a suggested marker of prenatal testosterone exposure, and the Cognitive Reflection Test (CRT) in a sample of 623 university students. In this pre-registered study, we test if we can replicate their findings in a general population sample of over 2,500 individuals from Germany. We find no statistically significant association between 2D:4D and the CRT in any of our primary hypothesis tests, or in any of our pre-registered exploratory analyses and robustness tests. The evidence is strong (based on the 99.5% confidence intervals in all three primary hypothesis tests) against effect sizes in the hypothesized direction larger than 0.075 CRT units (0.073 of the CRT standard deviation) for a one standard deviation change in 2D:4D.

The association of prenatal amniotic sex hormones and digit ratio (2D:4D) in children aged 5 to 70 months: A longitudinal study.

The sex difference of the 2D:4D digit ratio (female > male)-a proposed marker for prenatal testosterone exposure-is well established. Studies suggest it already exists in utero and is of moderate effect size in adulthood. However, evidence for the claim that 2D:4D reflects prenatal androgen action is limited, and the sex difference may exhibit lability during childhood. In the present study, 244 mothers were recruited in the course of an amniocentesis examination (performed between gestational weeks 14 and 18). Prenatal testosterone (T) and estradiol (E) levels were determined from amniotic fluid for boys and girls. The majority (97.4%, n = 114) of available female T levels (n = 117) were found below the level of quantification. Therefore, only male amniotic fluid data (n = 117) could be included for the analysis of associations between amniotic sex hormones (T levels and T to E ratio (T/E)) and 2D:4D. The families were then invited to each of the five consecutive follow-ups (ages: 5, 9, 20, 40, and 70 months) where children's 2D:4D was measured for both hands. The alternative marker D[r-l] reflects the directional asymmetry of 2D:4D (right subtracted by left 2D:4D) and was subsequently calculated as an additional measure for prenatal T exposure. No significant correlations between amniotic T or the T/E ratio (measured between week 14 and 18 of gestation) with 2D:4D respectively D[r-l] were observed for any time point. There was a significant sex difference (females > males) and a significant age effect with moderate correlations of 2D:4D between time points. 2D:4D increased between 20 and 40 months and between 40 and 70 months of age. The findings raise questions regarding the applicability of 2D:4D as a marker for prenatal androgen action and are discussed in terms of the reliability of obtained digit ratio data as well as in terms of the developmental timing of amniocentesis.

Prenatal Sex Hormone Exposure Is Associated with the Development of Autism Spectrum Disorder.

Sexual differentiation is a major developmental process. Sex differences resulting from sexual differentiation have attracted the attention of researchers. Unraveling what contributes to and underlies sex differences will provide valuable insights into the development of neurodevelopmental disorders that exhibit sex biases. Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects an individual's social interaction and communication abilities, and its male preponderance has been consistently reported in clinical studies. The etiology of male preponderance remains unclear, but progress has been made in studying prenatal sex hormone exposure. The present review examined studies that focused on the association between prenatal testosterone exposure and ASD development, as well as sex-specific behaviors in individuals with ASD. This review also included studies on maternal immune activation-induced developmental abnormalities that also showed striking sex differences in offspring and discussed its possible interacting roles in ASD so as to present a potential approach for future studies on sex biases in ASD.

Effects of prenatal testosterone exposure on the development of autism-like behaviours in offspring of Wistar rats.

A neurodevelopmental disease, autism spectrum disorder (ASD) occurs in males three times more commonly than girls. Higher prenatal testosterone exposure may result in autistic-like behaviour in boys, according to earlier research. It is unclear how fetal testosterone affects the development of autism. In this study, we tested the hypothesis that prenatal testosterone exposure in an animal model may result in autistic behaviours by modifying serotonin, dopamine, IGF-1 and oxytocin levels. Group 1 (control, n = 6) and Group 2 (testosterone undecanoate, n = 6) of female rats were randomly assigned. For 2-3days during the oestrus cycle, female rats were housed with a reproductive male (three females/one male). On the 10th day of gestation, rats in Group 1 received 1ml/kg% 0.9 NaCl saline, whereas rats in Group 2 received 250 mg/kg testosterone undecanoate. Until weaning on postnatal day 21 (P21), the mothers were permitted to care for their pups. On P21, 40 littermates-10 male and female for control and 10 male and female from mothers that exposed to testosterone-were arbitrarily split up and housed. On P50, these mature rats were tested for their behaviour. The rats were then sacrificed. The brain tissue was subjected to histological examinations as well as biochemical tests for homovanillic acid (HVA), 5-Hydroxyindoleacetic acid (5-HIAA), oxytocin and insulin-like growth factor-1 (IGF-1). The groups differed significantly in the behavioural examinations (three-chamber social test, passive avoidance learning analysis, open field test), with the testosterone-exposed groups exhibiting autistic symptoms to a higher extent. When compared with the control groups, testosterone exposure caused significant histological changes in the hippocampus CA1 and CA3 areas, including gliosis and cell death of neurons. In the testosterone-exposed groups, HVA, 5-HIAA and IGF-1 tissue expressions in the brain elevated, whereas oxytocin levels reduced. These findings point to a potential connection between neurodevelopmental disorders like ASD and exposure to testosterone during gestation. Overall, we revealed that prenatal testosterone exposure led to autistic traits by elevating serotonin, dopamine and IGF-1 levels while lowering oxytocin levels.

Investigation of the relationship between 2D:4D finger ratios and internet and smartphone addiction in middle school children

In humans, prenatal testosterone exposure affects a sexually dimorphic feature called the second-to-fourth digit ratio (2D:4D). Our research sought to better understand the connections among 2D:4D, Internet addiction (IA), and smartphone addiction (SPA) among middle school students. The study included 104 students aged between 10 and 14 years (mean age for girls: 11.3, the mean age for boys: 11.6), with 48 male and 56 female participants. Measurements of 2D:4D, hand length, and hand width were taken from the participants' hands. IA was assessed using the Young Internet Addiction Scale (YIAS), and SPA was assessed using the Smartphone Addiction Scale-Short Form (SAS-SF). In male participants, a negative correlation was found between the 2D:4D ratio and IA, while no correlation was observed in female participants. Both male and female participants showed a high correlation between IA and SPA. The study concludes that 2D:4D is an easily measurable and reliable marker for gender differentiation. It was found that male participants had higher levels of IA compared to female participants and that IA and SPA are strongly correlated in both genders.

The association between the 2D:4D ratio and psychopathic characteristics

Prior research has identified relations between prenatal testosterone exposure and various antisocial and criminal behaviors. However, less is known about the association between prenatal testosterone exposure and personality traits, such as psychopathy. This study used self-report and biometric data from a sample of undergraduates (n = 491) at a large southwestern university to examine the association between prenatal testosterone exposure (measured by the 2D:4D ratio) and three dimensions of psychopathy (i.e., callousness, egocentricity, and antisocial behavior). Analyses were stratified by sex to explore sex-specific biological underpinnings of psychopathy in young adulthood. Results showed that males scored significantly higher in psychopathic traits and reported significantly lower 2D:4D ratios, compared to females. Additionally, 2D:4D ratios were negatively associated with egocentricity in males, but not females. These findings contribute to a growing literature on the organizational effects that prenatal testosterone exposure may have on the development of different dimensions of psychopathy.

Anthropometric measures do not explain the 2D:4D ratio sexual dimorphism in 7-year-old children.

ObjectivesDigit ratio (2D:4D) might reflect prenatal testosterone exposure and has been used as a putative marker for androgen related outcomes. However, such associations might be inflicted by confounders. Application of 2D:4D in epidemiological research motivate identification of biological background determinants.We examined sex, anthropometric measures, and maternal factors as determinants of 2D:4D in Swedish 7‐year‐old children.MethodsThe study was embedded in the Swedish Environmental, Longitudinal, Mother and Child, Asthma and Allergy (SELMA) pregnancy cohort. A total of 870 pre‐pubertal children, median 7.5 years of age, were studied.A single assessor performed digit measurements from scanned photocopies using computer software. Child anthropometric measurements investigated were hand size, birthweight, recumbent birth length, standing height, weight, BMI, body fat percentage, and waist/hip circumference. Maternal factors included age, pregnancy length, parity, and education.ResultsWe found a significant sexual dimorphism regarding digit lengths and 2D:4D, boys on average presenting a lower 2D:4D than girls also after adjustment for summed finger lengths and body fatness. In crude analyses, maternal age correlated with 2D:4D across the whole population and in females but not in adjusted models. No other study variables were associated with 2D:4D.ConclusionDigit ratio showed sexual dimorphism at the age of seven and seems to represent a true sex difference rather than an artifact and bias from hand size, body size or body fat content. Among the rest of our investigated variables, we found no determinants constituting important confounders in future research on 2D:4D ratio.

Can Digit Ratio and Gender Identity Predict Preferences for Consumption Options With a Distinct Gender Image?

This study investigated whether individuals’ preferences for masculine (vs. feminine) consumption options could be predicted by a biological sex cue (the 2D:4D digit ratio; a biomarker linked to prenatal testosterone exposure), and a psychological gender cue (self-perceived gender identity). Chinese participants (N = 216) indicated their preferences for a series of binary options that differed in their perceived gender image (e.g., romantic comedy vs. action thriller; pop music vs. hard rock), with one of the options evaluated as relatively more feminine and the other viewed as comparably more masculine. Participants also self-reported their gender identity and the length of their index and ring fingers, which was used to calculate their 2D:4D digit ratios. A low (male-typical) digit ratio and a masculine gender identity were both associated with more masculine preferences, regardless of participants’ biological sex. However, a low digit ratio predicted preferences for masculine consumption options only in female participants with a masculine gender identity, but not in those with a feminine gender identity. These findings add to the literature on whether and when biological sex cues and psychological gender cues can predict preferences for options with a distinct gender image and suggest that the connection between these cues is more complex in women than in men.