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Originally Posted by nickipearl So, is it possible for his red-haired father and blonde-haired mother to have a brown-haired child? |
All of the details involved in the inheritance of hair color haven’t been worked out yet, but you can get a brown hair in a child using just two hair color genes. See
Human hair color - Wikipedia, the free encyclopedia. In this model there is 1 gene responsible for brown/blonde hair color with brown dominant over blonde. The second gene would determine red hair color with “not red” dominant over red. The 2 genes would interact (called epistasis) such that a “not red” trait (allele) is needed in order for the hair color to be blonde, brown or black.
So the red haired Dad could be carry the brown hair trait (allele) but have red hair color because he has only “red” alleles (this is called homozygous in genetics) at the second gene.
Mom would only need to pass on a “not red” allele at the second gene.
So where does black hair fit in? In this model the brown/blond gene has many alleles which are responsible for different shades of brown to black. This explanation “fits” and IMHO it is a reasonable theory … is it right? I don’t know, but I would expect that it is “right”, but oversimplified. Other genes certainly influence hair color. Hair color is determined by more than one gene (=polygenic) & the final color is subject to the influence of modifying genes & the environment. For example I had blonde hair as a kid, brown as an adult & now gray ;(
Not an intelligent design, but this is what you get when traits evolve.