How does genetic variation make a community more stable?

genetic variation in asexual species may have large effects on community and ecosystem functions, increasing their stability, productivity, and species richness.

Normally, members of an average community have downfalls in their DNA. However, as each being is completely different, different imperfections affect different people.

Now, imagine a community based on the offspring of two people. The imperfections passed on through the family line will grow stronger and stronger until a disease rare to normal human life strikes the family.

This is one of the reasons why incest is illegal (although still pretty gross even without that fact.)