Scientists say recent evidence suggests that it was likely the incestuous ways the Neanderthals that led to their extinction.

study published in the journal Nature shows the genetic structure of the parents of a female that lived 50,000-years ago are close enough to be considered brother and sister, first cousins or uncle and niece. Researchers used the DNA from a fossilized toe bone discovered in the Denisova Cave in Siberia several years ago to come to this conclusion.

Lead researcher David Reich from the Harvard Medical School in Boston says that the Neanderthal population was likely very small, which caused them to engage in inbreeding. This incestuous behavior rendered them unhealthy, and eventually killed them off.

“We know these people were mixing with their close relatives,” said Reich. “This seems to be something special about the Neanderthal population, it has this feature of inbreeding. We know this wasn’t a single event.”

It is suspected that Neanderthals also crossed over and mated with modern humans somewhere before their demise 30,000-years ago. Of course, this phenomenon could explain some of the shifty characters we have walking around in El Paso.