Apparently if you're aren't an inhabitant of sub-Saharan Africa, you're part Neanderthal. Which implies that, unlike what racial purists might argue (e.g. Aryan purity), it's the sub-Saharan Africans who are the purist of homo sapiens. Why is that? Because non sub-Saharan Africans have an X chromosome that contains some genetic material that is derived from Neanderthals, not Homo sapiens.
Yet it appears that very little Neanderthal DNA resides on the X chromosome (speculated to cause infertility). So on the one hand, our Neanderthal origins are found via DNA on the X chromosome, while at the same time very little Neanderthal DNA exists on it (in comparison to other chromosomes).