How do we explain the 1 twin being gifted then???
As far as I can tell, they aren't married, didn't have jobs, and were living with mama. That doesn't strike me as being gifted whatsoever. If, when they were young, they were able to finish high school or attend a "gifted" program, it is possible their mental condition deteriorated with age. I don't know what if any conditions they might have, but certainly there are known diseases that lead to brain deterioration at a later age.