I think you have an almost equally over simplified approach as Denis here. Having the same number of melanocytes means nothing, they only produce the melanin so the same number of melanocytes doesn't mean the same amount of melanin.
The only well characterised genetic determinant of skin colour at the moment is the types of Melanocortin1receptor (MC1R) an individual has, and there are over 60 identified human
MC1R alleles (
Rees, 2004).
The article I cite above states ...
Melanin is biosynthesized within melanosomes that, when mature, are passed to the surrounding keratinocytes. Visible skin color is therefore the result of the melanin in keratinocytes but is synthesized in melanocytes.
...
Studies of epidermal melanins (rather than hair melanins) are fewbecause they require skin biopsiesbut suggest that those with black skin have 2—3-fold as much melanin as Northern Europeans ...
TTFN,
WK
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