<sod>The 1993 study by [[Dean Hamer|Hamer]] examined 114 families of [[Homosexuality|gay]] men in the United States and found increased rates of homosexuality among maternal uncles and cousins, but not among paternal relatives. This pattern of inheritance suggested that there might be linked genes on the [[x-chromosome]], since males always inherit their copy of the x-chromosome from their mothers.  Polymorphisms  of [[genetic markers]] of the x-chromosome were analyzed for 40 families to see if a specific marker was shared by a disproportionate amount of brothers who were both gay.  The results showed that among gay brothers, the concordance rate for markers from the Xq28 region were significantly greater than expected for random Mendelian segregation, indicating that a link did exist in that small sample<ref name=Science /><eod>
<sod>The 1993 study by [[Dean Hamer|Hamer]] examined 114 families of [[Homosexuality|gay]] men in the United States and found increased rates of homosexuality among maternal uncles and cousins, but not among paternal relatives. This pattern of inheritance suggested that there might be linked genes on the [[x-chromosome]], since males always inherit their copy of the x-chromosome from their mothers.  Polymorphisms  of [[genetic markers]] of the x-chromosome were analyzed for 40 families to see if a specific marker was shared by a disproportionate amount of brothers who were both gay.  The results showed that among gay brothers, the concordance rate for markers from the Xq28 region were significantly greater than expected for random Mendelian segregation, indicating that a link did exist in that small sample.<ref name=Science /><eod>