Recessive mutations at the connexin-26 gene locus are now recognised as the cause of nearly half of all cases of genetic deafness in many populations. We suggest that this high frequency is only seen in populations with a long tradition of intermarriage among deaf people. Available data are consistent with the hypothesis that such marriages might well have contributed to the high frequency of connexin-26 deafness in the USA, and could represent a novel mechanism for maintaining specific genotypes at unexpectedly high frequencies.