Why does inbreeding increase the likelihood of the offspring having a genetic defect?
In: Biology
Because your genes are full of mistakes. The system has evolved to deal with this through redundancy. You have two copies of each^† gene, one from each parent, and most processes use one copy some of the time and the other copy the rest of the time. Only when both are broken do you have the most serious problem. When you inbreed, say by having a child with your sister, your child is a lot more likely to end up with two copies of one of your Mom’s genes. If that one has a bug, the child is in trouble.
† Except if you are male. You only get Y from your father, and X from your mother. There are genetic conditions, like some forms of hemophilia, which only effect males through their fathers.
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