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Updated: Jul 18, 2026

Assessing Differences in Sperm Competitive Ability in Drosophila
Published on: August 22, 2013
Sperm competition and the persistence of genes for male homosexuality
1Expert-center for Taxonomic Identification, University of Amsterdam, The Netherlands.
Abstract:
Homosexuality is increasingly recognized as having a genetic component. Why then does it persist, when common sense suggests that it should result in fewer offspring? Monozygotic-twin studies permit a rough estimate of the importance of genetics (70%) in the development of male homosexuality, and the proportion of homosexuals remains constant: Fisher's Theorem then tells us there is an advantage to the heterozygote, which we find need be no greater than 2%. Behavior and sperm competition suggest what this advantage might be.
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