Sequencing of the full Neanderthal genome suggests Neanderthals and some modern humans share some ancient genetic lineages. The authors of the study suggest that their findings are consistent with Neanderthal admixture of up to 4% in some populations. The reason for this admixture is not known. In August 2012, a study suggested that the DNA overlap is a remnant of a common ancestor of both Neanderthals and modern humans.