Stupidity Is Hereditary!

According to one of the two scientists that discovered DNA,
stupidity is a genetic illness. James Watson says, "If you are really stupid, I would call that an illness." He says that if you have a low IQ and don't have a diagnosed mental illness, then you suffer from a hereditary disorder that is pass on by way of the genes, like cystic fibrosis or hemophilia. So, just how would someone who's already an adult treat this "disorder?"