Do fertile women produce gay sons? Let's do a test of the "Beautiful Wives/Gay Sons" theory. According to Dienekes, sexual orientation is a combination of masculinity/femininity genetic factors inherited from parents. Gay men thus have more feminine parents, and for their mothers this means greater attractiveness and fertility. If this is true, homosexuals should come from larger than average families. Here are the mean number of siblings by gender and sexual orientation (GSS data).
Mean number of siblings
Straight 3.47 (N = 8,106)
Bisexual 4.93 (N = 54)
Gay 3.61 (N = 261)
Straight 3.71 (N = 9,314)
Bisexual 3.93 (N = 61)
Lesbian 3.43 (N = 187)
Gay and especially bisexual men come from larger families. While bisexual women also come from larger families, lesbians come from smaller families. More masculine mothers?
Normally with this kind of survey question, there is concern that traditional folks are underreporting their homosexuality, but here we see that more people from large and presumably more conservative families are admitting homosexual behavior (except for the lesbians).
One puzzle is that all the means seem too high. But keep in mind that this question has been asked since 1972 of people of all ages, so many folks come from families formed several decades ago. Plus, respondents are asked to include stepsiblings and adopted children. I checked and the means are skewed by the top few percent reporting huge family sizes, but even if they are removed, the pattern of the results stays the same.