Why does inbreeding often result in retarded children?

However, it's safe to say that prolonged and consistent inbreeding within a population usually does cause problems, whether mental or physical. The reason for this has to do with recessive genes. read more

However, it's safe to say that prolonged and consistent inbreeding within a population usually does cause problems, whether mental or physical. The reason for this has to do with recessive genes. Most everyone carries at least a handful of defective genes that, if they were allowed expression, would cause some type of disease. read more

Yes, this is why marriage between close relatives is generally illegal. The lack of diversity in the DNA of close relatives raises the likelihood of serious otherwise recessive birth defects getting passed on. read more

In the first family, however, you'd need one of the people with the B2 gene (which is 1/4 of the 3nd generation) to have children with some random, unrelated person who also happened to have the B2 gene, and they'd only have a 25% chance of having a child with the disorder. read more