Having engaged Dr Gallup in e-discussion, I can add another study to the mix:
Bogaert AF. Genital asymmetry in men. Human Reproduction 1997; 12(1): 68–72.
This study utilizes a vast store of data from men who were interviewed by the Kinsey Institute for Research in Sex, Gender and Reproduction from 1938 to 1963.
As noted on p 69 of Bogaert's article:
''... one (i.e. which testicle hangs lower) was marginally significant (P < 0.07). Given that some previous research (i.e. Chang et al., 1960) suggests nonright-handers are less likely than right-handers to have a lower left testicle, a directional (one-tailed) t-test for proportions was performed on this variable (i.e. which testicle hangs lower). As expected, a significant difference was observed (P < 0.05). Thus, a small but observable relationship seems to occur between genital asymmetry and handedness in men.''
The ethnic imbalance probably plays a role, as Bogaert notes, between Chang et al and his study of the Kinsey data.
I find it passing curious that the more recent researchers on this topic come from psychology departments, as opposed to medicine or physiology.
