There's also some slight evidence from Kinsey that gay men have longer penises, but (before you reach for a ruler) the finding is subject to the following caveat:
These findings are open to criticism because the measurements were made by the subjects themselves at home and not by an independent observer. (Gay men might be more tempted to exaggerate than straight men, or they might be more aroused by the sight of their erect penises, thus causing stronger erections.)� If correct, the result is inconsistent with the simplest form of the prenatal hormone hypothesis, which would predict gay men's penises to be smaller. There are various ways one could make the findings fit the hypothesis, but it may not be worth dwelling on this until a replication study has been done - which could be a while.