Back to Search
Start Over
The Second to Fourth Digit Ratio (2D:4D) in a Japanese Twin Sample: Heritability, Prenatal Hormone Transfer, and Association with Sexual Orientation
- Source :
- Archives of Sexual Behavior. 41:711-724
- Publication Year :
- 2012
- Publisher :
- Springer Science and Business Media LLC, 2012.
-
Abstract
- The second to fourth digit ratio has been argued to reflect prenatal hormonal influences and is reportedly associated with various psychological and behavioral traits, such as sexual orientation, cognitive abilities, and personality. We examined genetic and environmental influences on the second to fourth digit ratio (2D:4D) using a Japanese twin sample (N = 300). The genetic analysis showed substantial additive genetic influences for both right and left hand 2D:4D. The rest of the variance was explained mainly by environmental influences not shared within twin pairs. These findings were, in general, in accordance with preceding studies with primarily Caucasian twin samples. The bivariate genetic analysis revealed that the additive genetic influences were largely shared between the right and left hand, while the non-shared environmental influences were largely unique to each hand. Results from a comparison of opposite-sex and same-sex twins were not significant, although they were in the predicted direction according to the prenatal hormone transfer hypothesis. Female monozygotic twin pairs discordant in sexual orientation showed significant within-pair differences in left hand 2D:4D, where non-heterosexual twins had lower (more masculinized) 2D:4D. In addition, we found that non-heterosexual male MZ twins had larger (more feminized) 2D:4D than their heterosexual co-twins. These results suggest the existence of non-shared environmental influences that affect both 2D:4D and sexual orientation.
- Subjects :
- Male
Anthropometry
media_common.quotation_subject
Twins
Monozygotic twin
Cognition
Heritability
Affect (psychology)
Developmental psychology
Fingers
Japan
Arts and Humanities (miscellaneous)
Pregnancy
Prenatal Exposure Delayed Effects
Androgens
Sexual orientation
Humans
Personality
Female
Psychology
Association (psychology)
Sexuality
General Psychology
media_common
Subjects
Details
- ISSN :
- 15732800 and 00040002
- Volume :
- 41
- Database :
- OpenAIRE
- Journal :
- Archives of Sexual Behavior
- Accession number :
- edsair.doi.dedup.....d0251d10f69846f9e845651ac068a782