For once I share something with Curtaintwitcher. I agree that there are genetic differences between races.
My grandson suffers from anaemia and the doctors can not find a cause. One possibility they considered was sickle cell anaemia, which is limited in the ethnic groups who suffer from it and . Sickle cell disease is most commonly seen in people of African and Caribbean backgrounds. (quote from NHS site) and his parents were asked if they were absolutely sure that there was no one of Afro-Carribean origin in their family trees.
Other ethnic groups share certain genes that are less common in other groups.
Europeans (white people) are not the only or first ones to define people's position in society by colour. In the Indian caste system, among Middle Eastern people there is a hierarchy based on colour, also in other areas of Asia.
The attractions of women in almost any culture or race have always been defined by colour, the women who are 'fair' are considered of greater beauty than women who are dark. Dark haired, darker skinned women, usually meaning those with a rosier complexion or tanned are connected with all that that is evil.
The wicked stepmother is always shown as dark haired, and dark coloured, likewise Morgan-le-fey. The Virgin Mary, mother of Jesus Christ, is always seen as fair, except in a few more mdern interpretations, even though, as a native of Palestine she would, in fact, have been Middle Eastern in colouring with dark hair, dark eyes and a darker complexion than most European people.