[End of the road for the « homosexuality gene »]

Evidence for a "homosexuality gene" was claimed in the early 1990's on the basis of linkage studies that, by current criteria, were woefully underpowered. Indeed, follow up studies gave contradictory results. Genome-wide association studies, and very large databases with detailed genetic and phenotypic data, have made possible a re-examination of this issue. While modest heritability (ca. 0.3) for homosexuality is confirmed, no major locus is found and the genetic influence appears extremely polygenic. Thus, there is no single gene, or even small set of genes, that have a strong influence on homosexuality.