One study showed weak linkage to the Xq28 region, whereas a second in 1999 studying Canadian material consisting of 52 pairs of gay brothers found no statistically significant linkage in alleles and haplotypes and concluded against an X-linked male homosexuality gene.
•
The 1993 study by Hamer examined 114 families of gay men in the United States and found increased rates of homosexuality among maternal uncles and cousins, but not among paternal relatives.