Does the sex of one’s co-twin affect height and BMI in adulthood? A study of dizygotic adult twins from 31 cohorts

Abstract

BackgroundThe comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric traits, we compared mean height, body mass index (BMI), and the prevalence of being overweight or obese between men and women from OS and SS dizygotic twin pairs.MethodsThe data were derived from the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) database, and included 68,494 SS and 53,808 OS dizygotic twin individuals above the age of 20 years from 31 twin cohorts representing 19 countries. Zygosity was determined by questionnaires or DNA genotyping depending on the study. Multiple regression and logistic regression models adjusted for cohort, age, and birth year with the twin type as a predictor were carried out to compare height and BMI in twins from OS pairs with those from SS pairs and to calculate the adjusted odds ratios and 95% confidence intervals for being overweight or obese.ResultsOS females were, on average, 0.31 cm (95% confidence interval (CI) 0.20, 0.41) taller than SS females. OS males were also, on average, taller than SS males, but this difference was only 0.14 cm (95% CI 0.02, 0.27). Mean BMI and the prevalence of overweight or obesity did not differ between males and females from SS and OS twin pairs. The statistically significant differences between OS and SS twins for height were small and appeared to reflect our large sample size rather than meaningful differences of public health relevance.ConclusionsWe found no evidence to support the hypothesis that prenatal hormonal exposure or postnatal socialization (i.e., having grown up with a twin of the opposite sex) has a major impact on height and BMI in adulthood.Electronic supplementary materialThe online version of this article (doi:10.1186/s13293-017-0134-x) contains supplementary material, which is available to authorized users.

The CODATwins Project: The Current Status and Recent Findings of COllaborative Project of Development of Anthropometrical Measures in Twins

“…Using the twin design, we demonstrated that intrauterine conditions affecting smaller birth size are associated with shorter height and lower BMI from early childhood to adulthood (Jelenkovic et al, 2017;Jelenkovic et al, 2018a), which are consistent with prior studies. On the other hand, our findings that birthweight was only weakly associated with adult education in discordant twin pairs (Jelenkovic et al, 2018c) and that males and females having opposite-sex co-twins showed no consistent differences as compared to those having same-sex co-twins in height and BMI (Bogl et al, 2017) are not consistent with previous hypotheses. Because there is a well-known tendency to publish positive results (Thornton and Lee, 2000), these types of large collaborative studies are important to validly test hypotheses and estimate effect sizes not inflated by publication bias.…”

Testing the twin testosterone transfer hypothesis—intergenerational analysis of 317 dizygotic twins born in Aberdeen, Scotland

“…We found that females from opposite-sex twin pairs did not differ in terms of reproductive outcomes from females from same-sex twins, rather, they had the same chances of getting pregnant and having children compared to women with a female co-twin. In accordance with other studies, baseline characteristics such as birthweight of female twins and their adult BMI were not different between opposite-sex and same-sex twin pairs ( Bogl et al , 2017 ; Jelenkovic et al , 2018 ). Overall, our findings agree with what Medland et al (2008) reported in a study using three cohorts (Australia, The Netherlands and USA) and evaluating a total of 1979 females from same-sex twin pairs and 913 females from opposite-sex twin pairs.…”

Basic Human Body Dimensions Relate to Alcohol Dependence and Predict Hospital Readmission

“…Moreover, the smaller body height of alcohol-dependent males in comparison to healthy control males detected here is contradictory to the expectations based on findings from the TTT. In males, a male co-twin in comparison to a female co-twin reduces both the risk for later alcohol dependence [36] and body height [63], although the effect sizes were small in both investigations. However, this entails the prediction of larger body height in alcohol-dependent males.…”