Finger-length ratios show evidence of prenatal hormone-transfer between opposite-sex twins.
Finger-length ratio (second to fourth finger; 2D:4D) has been associated with various measures thought to be related to prenatal androgens. In addition, hormone-transfer theory posits that hormones can transfer between twins. We examined 2D:4D in same-sex (SS) and opposite-sex (OS) dizygotic twins to test both propositions. Results show that 2D:4D is masculinized in OS females compared to SS females. This provides strong evidence that 2D:4D is laid down prenatally, and that hormones (likely androgens) can transfer from male to female fetuses. Implications for developmental timeframes for both hormone-transfer and 2D:4D are discussed.
van Anders
Sari M
SM
Department of Psychology, Simon Fraser University, Burnaby BC, Canada. saria@sfu.ca
Vernon
Philip A
PA
Wilbur
Christopher J
CJ
D000293:Adolescent; D000886:Anthropometry; D002648:Child; D002675:Child, Preschool; D005260:Female; D005385:Fingers / Q000033:anatomy & histology*; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D006801:Humans; D008297:Male; D009929:Organ Size; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012727:Sex Characteristics; D014429:Twins, Dizygotic / Q000502:physiology*
D012739:Gonadal Steroid Hormones