Perhaps a succinct way of phrasing this is that cultures can change much faster (or much slower) than genetic composition of a people, so looking at genetics can give a very misleading impression of a society.<p>I think a good example of some part of this is southeast Asia. Cambodia, Burma, and Lao are all adjacent to Thailand. The people that makeup these 4 nations visibly share an extremely recent common ancestor. Yet, the cultures and groups of peoples are all quite different and there is even extreme 'racism' among them, which is somewhat ironic.<p>If you studied these people based on genetic makeup from a distant future it'd just look like a mostly homogenous glob, but that's not even remotely close to accurate. And so an interpretation based primarily on genetics would be completely misleading.