PROCREATIVE INSTINCT AS A CONTRIBUTORY FACTOR TO PREVALENCE OF HEREDITARY BLINDNESS

Abstract

The same, or different, autosomal dominant disease in both parents puts a child at 75% risk of having one or both diseases. The risk of hereditary disease is even higher (100%) when both parents have the same autosomal recessive disease. The blind tend to marry the blind, partly because of the bond of shared affliction and partly because they are usually segregated in blind schools and blind workshops. The proportion of those with hereditary blindness in these institutions is now high. Couples in which both partners have hereditary disease often take high risks of having children with "hyperendemic institutional genetic blindness"—perhaps because those with congenital or infantile blindness value sight less than do those who lose their sight later on, and perhaps because the power of the procreative instinct is strong enough to override more objective risk assessment. The procreative instinct is also an important cause of the exponential growth in world population.