Experts claim to have found scientific reasons why opposites attract, which may shed some light on how humans choose their mates and help them further understand problems of fertility, conception and gestation.

A team of Brazilian scientists has found that people with different histocompatibility complexes (MHC) -- the set of genes in most vertebrates that plays an important role in the functioning of the immune system, autoimmunity, and determines reproductive outcomes -- were more likely to choose each other as mates than those with similar MHCs, dispelling the belief that people are drawn to each other for their similarities.