Mother and son in New Mexico face jail time for incestuous relationship

[FatAndFaithless]

Tell me what the problem is.

Children of sexual relations between close relatives suffer from genetic defects and illnesses to a greater extent than normal children. There was this obscure family of Spanish nobles called the Hapsburgs who are a perfect illustration of what happens when each generation marries its first cousin. Google them some time.

There are plenty of non-related couples who have high risks of certain birth defects as well, just by the nature of their genes and how they match up.  We don't make laws against them having kids.