Cancer by negative heterosis: breast and ovarian cancer excess in hybrids of inbred ethnic groups

In Pakistan, conditions were favorable for cancer development by heterosis because country has a high number of different ethnic groups and brotherhoods all of which have a higher rate of homozygosity due to a high frequency of consanguineous marriages, and marriages between members of different groups occurred because of intense population mixing. Result was birth of a large number of inter-ethnic/brotherhood hybrids (heterozygotes), some of which have developed cancer by heterosis.