[quote]An increase in homozygotes has diverging effects. A homozygote encoding a congenital birth defect will produce children with birth defects, but homozygotes that do not encode for congenital birth defects will decrease the number of carriers in a population. The overall consequences of these diverging effects depends in part on the size of the population. In small populations, as long as children born with heritable birth defects die (or are killed) before they reproduce, the ultimate effect of inbreeding will be to decrease the frequency of defective genes in the population; over time the gene pool will be healthier. In larger populations, however, it is more likely that large numbers of carriers will survive and mate, leading to more constant rates of birth defects.[[/quote]