If we use Ayala's figures, there would be no problem at all. Furthermore, several genes are known to exist in multiple copies, and some traits, like color, weight, and intelligence, depend on the cumulative effect of genes at two or more loci. Such mutations impose an increasingly heavy genetic burden or genetic load on a species. The list of human mutational disorders, or genetic diseases, for example, has already passed 1500, and it is continuing to grow. By elimination of the unfit, natural selection reduces the harmful effects of mutations on a population, but it cannot solve the evolutionist's genetic burden problem entirely.
Most mutations are recessive.
As time goes on, existing mutants build up to a complex equilibrium point, and new mutations are continually occurring. Odd with time, such marriages are considered most unwise. Genetic burden, then, becomes a staggering problerti for evolutionists trying to explain the enormous adaptive variation within species on the basis of mutations. For any conceivable favorable mutation, a species must pay the pi-ice or bear the burden of more than 1000 harmful mutations of that gene. As mutational load increases with time, the survival of the species will be threatened as indtiiigs produce a greater percentage of offspring carrying serious genetic defects.