well, it is definitely genetic, but the other's don't really make any sense. this is my favorite explanation regarding the evolution of male pattern baldness,
"A well-polished bald male head was often used by tribes of cavemen to blind predators. As a result every cavemen hunting group of 8 had one bald member, and thus thousands of years later 1 in 8 men experience early on set of baldness." hahaha
it's just one of those things that we evolved with. We see these things all around us, however, never give them too much consideration because they are not as socially significant. It occurs in other primates as well. It may have just been caused by a mutation somewhere along our evolution that "stuck". One theory is that men with male pattern baldness exude a level of maturity and this is desirable in natural selection. Why it's patterned is anybodies guess. Why do we grow patches of hair on our backs??? Why can more hair start to grow in otherwise bald areas of out bodies as we age?? It's all in gene expression and it S*CKS MY F*CKING BALLS!!!!