In the birth of the gay men accused the older brothers

Canadian and American scientists have offered a biological explanation for the effect of birth order of the brothers of the relationship between the number of older brothers maternal and homosexuality youngest child. A study published in the journal Proceedings of the National Academy of Sciences.

The experts found that in the blood plasma of women who have a gay son, you have exceeded the level of antibodies to the protein NLGN4Y, compared with mothers who only have heterosexual children. The dependence became stronger in the case of families with little brother gay older brothers-heterosexual.

The study authors note, is “an important step forward in understanding the origins of sexual orientation in men”. It also allows you to assume that homosexual sexual orientation is associated with “immune response of the maternal organism to the protein, important in embryonic development of the male brain”, scientists believe.

The NLGN4Y gene encodes the eponymous protein responsible for the ability of cells to communicate with extracellular matrix and other cells, in particular, for the formation of synaptic connections. The expression of NLGN4Y is observed mainly in brain and prostate gland.