Maternal Genes, Family Size Linked To Homosexuality

Genes handed down by one's mother and having a large number of older brothers may determine whether someone is a homosexual, according to a study published on Wednesday. Put together, these two factors may account for perhaps 20 per cent of the prevalence of homosexuality, although social and cultural influences probably make up most of the rest, it suggests. Psychologists at the University of Padova asked 98 homosexual men and 100 heterosexual men in northern Italy to fill out a confidential questionnaire detailing their sexual orientation and that of their siblings, first cousins, parents, aunts, uncles and grandparents.