A Student asked me a while back what are the chances for a
Male whose father is Negroid(Black) and mother is Caucasian(White),
rendering the man half Black and half white, to produce a child from a
fully caucasian female that has Blonde hair and Blue eyes?
Skin color is determined by multiple genes and ends up being a mixing of
these genes. As a result the two parents will tone the child's skin to a
degree representing a combination. Like mixing dark brown paint with white
paint to develop a light brown composition.
Skin color is now believed to be a polygenic trait governed by three sets of
genes. This means that each parent contributes three possibilities (alleles)
and each allele is additive; in other words each allele carries its own
weight. Let's say that the father is black and has 2 light colored alleles
and 4 dark colored alleles. Let's say the mother is white and carries 4
light colored alleles and 2 dark colored alleles. The father gives 2 light
alleles and one dark and the mother gives all three light alleles. The
daughter would have 5 light colored alleles and one dark and would be lighter
than her mother. The same could hold true for eye color because now it looks
as though eye color is more complicated than brown over blue as we have
always been taught. But even if it is that simple, if the father had dark
eyes but carried a blue allele, and the mother had blue eyes, the probability
would be 50% that the daughter would have blue eyes. The same could hold
true for blond hair. So yes it is possible.
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Update: June 2012