Sergey Gavrilets AFF1 AFF2 and William R. Rice AFF3

AFF1 Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 
37996, USA
AFF2 Department of Mathematics, University of Tennessee, Knoxville, TN 37996, USA
AFF3 Department of Ecology, Evolution & Marine Biology, University of California, Santa 
Barbara, CA 93106-9610 USA

Abstract:

Homosexuality is a common occurrence in humans and other species, yet its genetic and 
evolutionary basis is poorly understood. Here, we formulate and study a series of simple 
mathematical models for the purpose of predicting empirical patterns that can be used to 
determine the form of selection that leads to polymorphism of genes influencing 
homosexuality. Specifically, we develop theory to make contrasting predictions about the 
genetic characteristics of genes influencing homosexuality including: (i) chromosomal 
location, (ii) dominance among segregating alleles and (iii) effect sizes that distinguish 
between the two major models for their polymorphism: the overdominance and sexual 
antagonism models. We conclude that the measurement of the genetic characteristics of 
quantitative trait loci (QTLs) found in genomic screens for genes influencing homosexuality 
can be highly informative in resolving the form of natural selection maintaining their 
polymorphism.