Another Woolly-Hair Mutation in Man

Another Woolly-Hair Mutation in Man

The Journal of Heredity
Volume 25, Number 9 (September 1934)
pages 337-340

C. Ph. Schokking
Rotterdam, Holland

A Dutch peasant family living near Leiden carries a dominant gene for a type of woolly hair characteristic of the Negro races. This is not to be explained as due to race crossing for two reasons.  In the first place there is no tradition in the family of an infusion of Negro blood and no other evidence of anything but pure Dutch ancestry. Furthermore, hair form behaves in racial crosses not as a simple dominant character but as a “blending” character (in which to or more genes are involved).  Thus simple mendelian inheritance of hair form is not found in Negro-white crosses. Among such hybrids various degrees of curly and wavy hair are observed, and in later generations wooly hare may appear but only where both parents are partly Negro. Thus the occurrence of woolly hair in this family is clear due to mutation rather than race hybridization.

While studying twins in Leiden in 1929 and 1930, I encountered a pair of non-identical twin sisters, one of whom had remarkably curly hair. Since little is known of the inheritance of such genuine woolly hair among Europeans, I followed up the history of this pair. It soon transpired that in the village of Rijnsburg, near Leiden, whence the girls came, many woolly-haired persons were to be found, and that all of these belonged to the same family. After a deal of effort I was able to put together a pedigree chart covering five generations (Figure 3). The founder of the family had already died and no photograph of him was to be had, but an old Rijnsburger, who knew both this man and his father, was able to give me definite information that both of them had woolly hair…

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