For me it is this, although not that my own mom and favored boys over girls it is actually the opposite, but it is the WHOLE culture, boys are favored to a certain extent. In addition to this:
1) my father, brothers are just AWSOME sons, very loving caring funny just would do ANYTHING to make their Moms happy.
2) We are the ONLY married couple in both families( mines and DH) who don't have a son, whenever all the guys go out for games my husband is the only one with no son :(