A family study of congenital inguinal hernia.

In fathers and mothers of 707 index patients with operated indirect congenital inguinal hernia (CIH) born in Budapest during the years 1962-1966 the frequency of CIH was two and five to six times higher, respectively, than in the general population. The rate of affected sibs was higher than that of parents but was greatly dependent on the sex of the index patient. Heritability estimates of CIH vary significantly in parents (0.35 +/- 0.12) and in sibs (0.78 +/- 0.14). In twins the heritability is 0.77. These data agree with the multifactorial threshold model involving dominance variance.