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Chapter 25 GENES AND SKIN COLOR: THE MORE THE MERRIER The number of genes determining skin color inheritance in humans cannot be determined until detailed family studies have been undertaken. Pamela Byard! Skin color is undoubtedly inherited, but misconceptions about it are many and have been repeated in literature. For instance, in one of Conan Doyle'S Sherlock Holmes adventures, a little girl wears a yellow mask. The reason for this strange behavior is that the mother is afraid she would lose the love of her husband if he knew that she had a child from a former husband, an African American, who had died three years earlier. Showing the portrait of her deceased husband to the astonished Holmes, Watson and her second husband, the woman said: That is John Hector of Atlanta and a nobler man never walked the earth. I cut myself off from my race in order to wed him but never once while he lived did I for an instant regret it. It was my misfortune that our only child took after his people rather than mine. It is often so in such matches, and little Lucy is darker than her father was. But dark or fair, she is my own little girly and her mother's pet.2 There is a problem with this story. It is impossible for a child who has one very light-skinned parent, as Lucy did (her mother), and one dark-skinned parent (her father), to be even as dark as the darker parent , let alone darker than that parent. It can be stated with certainty that no authenticated instance of such a birth has ever been reported. Nor has there been any well-documented case in which dark-skinned children were born to very light-skinned parents. On the contrary, in the few instances in which this was alleged to have happened, 193 194 Alain Core os investigation revealed that the reported instance was based on hearsay and not observed fact, or that it was the result of concealed illegitimacy involving a darkly-pigmented parent. We can make allowance for Conan Doyle's mistaken idea. After all, in his time, the science of genetics had not been born, and no one could have explained to him why little Lucy could not be darker than her father. For approximately eighty years we have tried to explain skin-color differences by assuming that from two to five pairs of genes were involved, that very light-skinned individuals have no genes for pigmentation, and that very dark-skinned individuals have all of them. It was further assumed that there was no dominance and recessiveness in the genes for skin pigmentation, and that the effects of the genes involved were additive, i.e., that one individual who has two genes for pigmentation would be twice as dark as one who has only one. It follows from these assumptions that no genes for color are in hiding. "White," i.e., very light-skinned persons, cannot transmit to their children any gene for pigmentation that they do not have. The only genes for pigmentation that these children have come from the other parent if he or she happens to have a dark complexion. Therefore, children cannot have more genes for pigmentation than their darker parent and cannot be darker than him or her. The first studies of the genetics of skin color date from 1913, when Charles Davenport and Gertrude Davenport.3 became interested in the inheritance of differences in skin color. They carried out their investigations in Jamaica and Bermuda, where marriages among "blacks and whites" are fairly common, since they were not forbidden as they were in many places in the United States. There, the ancestry of the parents could be traced fairly clearly. The reader should note that, since all of us have some color in our skin, the problem that the Davenports attacked was different from the problem of inheritance of skin color in general. They were dealing with the inheritance of the differences in skin color between two human groups. The investigators were able to find six families in which one of the grandparents was light-skinned and the other dark, and which produced thirty-two grandchildren. They measured skin color of members by means of a "color top." Colored paper disks were overlapped in such a way that varying proportions of each color were exposed. When the top was spun, the colors seemed to blend together. By varying the...

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