Reanalysis of Bell, Weinberg, and Hammersmith's data on birth order, sibling sex ratio, and parental age in homosexual men

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.