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107
In families 1, 2, and 4, there are seen examples of the working of the Mendelian
hypothesis, in which pure recessives (deafness being a recessive character) "breed
true." In family 2, it is true that the mother suffered from acquired deafness, but
both the parents came of deaf families. In family 3, the effect of mating between
an individual of a deaf family and an acquired deaf case is seen. It has been
established by Fay (" Marriages of the Deaf in America," p. 128) that "Congenitally
deaf persons, whether they are married to one another, to adventitiously deaf, or
to hearing partners, are more liable to have deaf offspring than are adventitiously
deaf persons."
Of the 33 cases of sporadic deaf birth, in four cases the condition was attributed
to air raids. In one of these the mother stated that she received a severe
electric shock by the touching of a live wire during a raid. In one case the
mother, while pregnant, was badly frightened by the Silvertown explosion and
lost her speech for some days after.