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Digit Ratio (2D:4D; Right-Left 2D:4D) and Multiple Phenotypes for Same-Sex Attraction: The BBC Internet Study
John T Manning1, Bernhard Fink2,3,4, Robert Trivers5
1Applied Sports, Technology, Exercise, and Medicine (A-STEM), Swansea University, Swansea, UK.
Archives of Sexual Behavior
|October 17, 2023
Summary
Prenatal androgen levels may influence same-sex attraction. Both low and high levels appear linked in men, while high levels are suggested for women, with digit ratio (2D:4D) as an indicator.
Area of Science:
- Endocrinology
- Human Sexuality
- Behavioral Science
Background:
- Prenatal androgen exposure is hypothesized to influence sexual orientation.
- Digit ratio (2D:4D) is a proposed marker for prenatal androgen exposure.
- Previous studies show mixed results regarding 2D:4D and same-sex attraction.
Purpose of the Study:
- To investigate the association between prenatal androgen markers (2D:4D and 2D:4D difference between right and left hands, Dr-l) and same-sex attraction.
- To explore potential non-linear relationships and differing patterns in men and women.
Main Methods:
- Analysis of a large dataset (BBC Internet study) including over 100,000 men and 80,000 women.
- Examination of linear and U-shaped associations between 2D:4D, Dr-l, and same-sex attraction scores.
Main Results:
- Positive linear associations found between 2D:4D and same-sex attraction in men.
- Negative linear associations found between 2D:4D and Dr-l with same-sex attraction in women.
- A U-shaped association was observed between Dr-l and same-sex attraction in men.
Conclusions:
- Findings suggest that both low and high prenatal androgen may be implicated in male homosexuality.
- High prenatal androgen is potentially linked to female homosexuality.
- Significant lateral differences in androgen sensitivity (Dr-l) may correlate with increased same-sex attraction in men.
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