Birth Order and Gay Orientation

According to a large Norwegian study, “the more older brothers a boy has, the more likely he is to be gay. This ‘fraternal order effect’ is thought to stem from prenatal influences, such as male hormone levels in the womb (because boys raised with nonbiological older brothers are not more likely to be gay).” For those of you who have asked, the October/November 2007 issue of Scientific American Mind (www.sciammind.com) contains an article about the impact of birth order.