Taxometric analyses of sexual orientation and gender identity

Taxa are nonarbitrary classes whose existence is an empirical question and not a matter of mere semantic convenience. Taxometric procedures detect whe ther numerical relations between purported indicators of conjectured taxa b ear the hallmarks of true taxa. On the basis of theoretical considerations, the current study tested whether taxa underlie sexual orientation and rela ted measures of gender identity. Two taxometric procedures, maximum covaria nce, making hits maximum (MAXCOV) and mean above minus below a cut (MAMBAC) , were applied to Kinsey Scales and measures of childhood gender nonconform ity and adult gender identity in a sample of nearly 5,000 members of the Au stralian Twin Registry. Results suggest that latent taxa underlie these mea sures. About 12-15% of men and 5-10% of women belong to latent taxa associa ted with homosexual preference. These percentages are greater than those of individuals who report homosexual preference, however, and hence it appear s that an appreciable proportion of individuals in these taxa have heterose xual preference. An understanding of the origins of these latent taxa may b e important to understanding the development of sexual orientation and gend er identity.