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The genetic material common to all races must have been present in our first parents. Certain racial/ethnic qualities, which by the way are amazingly superficial in comparison to our overall similarities, developed over time as populations separated after the flood, intermarried and responded to differing environments.
The key thing is that we humans spring from the same source and as Paul said in an insight amazing for his day and age:
Acts 17:26 And He has made from one blood every nation of men to dwell on all the face of the earth...
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I hope you have found this helpful.