Apparently, here’s the study that says 52% of identical twins are gay.  In fact, let me quote you the whole thing here:

 

 

A genetic study of male sexual orientation

J. M. Bailey and R. C. Pillard
Department of Psychology, Northwestern University, Evanston, Ill 60208.

Homosexual male probands with monozygotic cotwins, dizygotic cotwins, or adoptive brothers were recruited using homophile publications. Sexual orientation of relatives was assessed either by asking relatives directly, or when this was impossible, asking the probands. Of the relatives whose sexual orientation could be rated, 52% (29/56) of monozygotic cotwins, 22% (12/54) of dizygotic cotwins, and 11% (6/57) of adoptive brothers were homosexual. Heritabilities were substantial under a wide range of assumptions about the population base rate of homosexuality and ascertainment bias. However, the rate of homosexuality among nontwin biological siblings, as reported by probands, 9.2% (13/142), was significantly lower than would be predicted by a simple genetic hypothesis and other published reports. A proband’s self-reported history of childhood gender non-conformity did not predict homosexuality in relatives in any of the three subsamples. Thus, childhood gender nonconformity does not appear to be an indicator of genetic loading for homosexuality. Cotwins from concordant monozygotic pairs were very similar for childhood gender nonconformity.

 

Interesting stuff.  Did you notice how the 52% was derrived?  That’s right, from a pool of a whopping 56 people.  That means each person counts for 1.8% of the percentage total!  So if such a great number as 5 people lied in saying their identical twin was gay too, there would be only 42.9% gay correlation.

And this study wasn’t exactly a random sampling either.  Instead, it was a sampling of people who were reading “homophile publications.”  Nor was this study exactly unbiased either, but instead relied on “a wide range of assumptions about the population base rate of homosexuality and ascertainment bias.”

Naturally, the study doesn’t show us how they define “homosexual” either.

Perhaps all of the above are good indications as to why this study, conducted back in 1991, isn’t that big of a deal after all….