title: Heritability of testosterone levels in 12-year-old twins and its relation to pubertal development.
abstract: The aim of this study was to estimate the heritability of variation in testosterone levels in 12-year-old children, and to explore the overlap in genetic and environmental influences on circulating testosterone levels and androgen-dependent pubertal development. Midday salivary testosterone samples were collected on 2 consecutive days in a sample of 183 unselected twin pairs. Androgen-induced pubertal development was assessed using self-report Tanner scales of pubic hair development (boys and girls) and genital development (boys). A significant contribution of genetic effects to the variance in testosterone levels was found. Heritability was approximately 50% in both boys and girls. The remaining proportion of the variance in testosterone levels could be explained by nonshared environmental influences. The relatively high correlation between testosterone levels of opposite-sex dizygotic twins suggests that sex differences in genes influencing variation in testosterone levels have not yet developed in pre- and early puberty. Variance in pubertal development was explained by a large genetic component, moderate shared environmental influences, and a small nonshared environmental effect. Testosterone levels correlated moderately (r = .31) with pubertal development; the covariance between testosterone levels and pubertal development was entirely accounted for by genetic influences.
authors.affiliation: Department of Biological Psychology, Vrije Universiteit, Amsterdam, the Netherlands. Ra.Hoekstra@psy.vu.nl
authors.forename: Rosa A
authors.initials: RA
authors.lastname: Hoekstra
authors.forename: Meike
authors.initials: M
authors.lastname: Bartels
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
mesh_terms: D002648:Child; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011627:Puberty / Q000235:genetics* / Q000378:metabolism; D012463:Saliva / Q000378:metabolism; D013738:Testolactone / Q000032:analysis; D014429:Twins, Dizygotic / Q000235:genetics* / Q000378:metabolism; D014430:Twins, Monozygotic / Q000235:genetics* / Q000378:metabolism
chemical_list: D013738:Testolactone