LINKAGE BETWEEN SEXUAL ORIENTATION AND CHROMOSOME XQ28 IN MALES BUT NOT IN FEMALES

We have extended our analysis of the role of the long arm of the X chr omosome (Xq28) in sexual orientation by DNA linkage analyses of two ne wly ascertained series of families that contained either two gay broth ers or two lesbian sisters as well as heterosexual siblings. Linkage b etween the Xq28 markers and sexual orientation was detected for the ga y male families but not for the lesbian families or for families that failed to meet defined inclusion criteria for the study of sex-linked sexual orientation. Our results corroborate the previously reported li nkage between Xq28 and male homosexuality in selected kinships and sug gest that this region contains a locus that influences individual vari ations in sexual orientation in men but not in women.