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To the Editor:
—In his paper on this subject (The Journal, May 15, 1915, p. 1640), Dr. Brandeis, while by no means deciding the question whether polydactylism is a dominant or a recessive characteristic, seems to assume that the mendelian dominance of either polydactylism or five-fingeredness is an irregular or an imperfect dominance. It does not appear—on carefully considering the family history with which he deals or the other family trees quoted—that such an assumption is really necessary.Prima facie, I should be more apt to assume from these tables that polydactylism is a truly recessive trait; perhaps also venturing the suggestion that a proportion of the human race, larger than one would at first suppose, may have received from their parents factors that, under proper mating conditions, might bring this recessive trait to light.Assuming these things, let us suppose that Individual 8 in Dr. Brandeis' tree is really
Tymms WR. Polydactylism as a Hereditary Character. JAMA. 1915;LXIV(23):1931. doi:10.1001/jama.1915.02570490047026