Before revision: Biochemical evidence for this hypothesis was identified in 2017, finding mothers with a gay son, particularly those with older brothers, had heightened levels of antibodies to the NLGN4Y Y-protein than mothers with heterosexual sons.
After revision: Biochemical evidence for this hypothesis was identified in 2017, finding mothers with a homosexual son, particularly those with older brothers, had heightened levels of antibodies to the NLGN4Y Y-protein than mothers with heterosexual sons.