1. Range of Homo neanderthalensis. Peoples of non-African descent have from one to five percent Neanderthal DNA in their genetic makeup.
2. Rates of interbreeding. From high degrees of consanguinity (light) to low degrees of consanguinity (dark).
Christian canon law followed Roman civil law, which forbade marriage within four degrees of consanguinity. This mandate has persisted among Christians of the Middle East.