The rh negative/positive factor is a real issue, not fake in the slightest. The rh negative trait is recessive and only about 7% of the world population expresses this trait. The rh negative factor does not have enough potency in the general population to cause an issue with population numbers. Plus, it is only an issue when the woman is rh negative and the man is rh positive, and only when the child acquires the father's rh factor. Our ancestors had very little trouble having children since over 90% of the world population is rh positive.