The authors compared parental age, birth order, and sex ratio of
siblings for 575 homosexual men and 284 heterosexual men, matched on age
and education. They were originally part of Bell, Weinberg, and
Hammersmith's large-scale study of male and female homosexuality. The
results confirmed the previous findings that homosexual men have older
fathers and later births than do heterosexual men but not the finding that
homosexual men have larger proportions of brothers. The collective findings
suggest that birth order is perhaps the single most reliable demographic
difference between homosexual and heterosexual men.Abstract Teaser