The dermatoglyphic characteristics of transsexuals: is there evidence for an organizing effect of sex hormones

It has been proposed that gender identity and sexual orientation are influe nced by the prenatal sex steroid milieu. Human dermatoglyphics and brain as ymmetry have also been ascribed to prenatal hormone levels. This study inve stigated dermatoglyphics (total ridge count and finger ridge asymmetry) in 184 male-to-female transsexuals and 110 female-to-male transsexuals. In a s ubgroup, the relationship between dermatoglyphic asymmetry and spatial abil ity was tested. All investigations included controls. For all subjects hand preference and sexual orientation were noted. We hypothesized that the der matoglyphics of male-to-female transsexuals would show similarities with co ntrol women and those of female-to-male transsexuals with control men. Our results showed a trend for a sex difference in total ridge count (P < .1) b etween genetic males and females, but no difference in directional asymmetr y was found. Contrary to our expectations, the total ridge count and finger ridge asymmetry of transsexuals were similar to their genetic sex controls . Additionally, directional asymmetry was neither related to sexual orienta tion, nor to different aspects of spatial ability. In conclusion, we were u nable to demonstrate that our chosen dermatoglyphic variables, total ridge count and finger ridge asymmetry are related to Sender identity and sexual orientation in adult transsexuals. Hence, we found no support for a prenata l hormonal influence on these characteristics, at least insofar as dermatog lyphics may be regarded as a biological marker of organizing hormonal effec ts. (C) 2000 Elsevier Science Ltd. All rights reserved.