Not only fat people pollute gene pool. Nature take care that only strongest, fittest, smarter survive and spread 'good' genes. Humans disrupt natural process. Dumbest, weak individuals thanks to help of society have bigger chance to survive and spread his bad genes to rest of population. Even more, society give a additional support to weakest individuals. For fat people....... just look around, fat couple often have fat children. They don't care, even encourage his kids to don't give a fuck... and continue to be ball of lard.