the proper terms for genetic traits would be recessive and dominant, not weaker and stronger.
For skin color, it is not all or none, there are several genes involved in making the pigment melanin, and their expression is incomplete dominance, meaning if you cross white with black you don’t get black, but something in between. There is a wide range of skin color. Environment also affects pigment production- like tanning. It would be interesting to see if Ashkenazim and Mid-eastern Jews had similar skin color genetics, but if environmental factors influenced the actual melanin production.
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