system
Given the following post, respond as if you're commenting on Reddit:
human
eli5 If inbreeding causes a lack of genetics, how is there such genetic diversity?

How is there such genetic diversity now if inbreeding causes a lack of it? How did that not happen when there wasn’t a lot of animals on the planet? Or was it that there were a lot of land animals by the time that was an issue to not have to worry about it?
gpt
Genetic diversity happens through random mutation in DNA. Some mutations are good, some are bad, and most are neutral. These mutations build up over generations, leading to genetic diversity.

Of the mutations that are bad, many are what's called "recessive." That means you need to get two bad copies of the gene to get the bad trait. If your parents are very genetically distinct, it is unlikely that both will be able to give you the same bad mutation. If your parents are closely related, they are more likely to give you the same "bad" gene.