 Vilain also researches sex differences in the brain, most notably the biology of gender identity and sexual orientation.Along with other collaborators, Vilain and his team have published papers on the expression of sex-regulating genes effecting the differentiation of brains using mouse models and studied the role the SRY gene plays in regulating adult brain function.In 2006, his team, along with geneticist Dean Hamer, published research studying the linkage of gay males and markers on their mothers’ X chromosome.