The connection I see is between being f(*&ked up and not taking good care of your baby. Notice how the association with the mother alone is almost as significant as the association with both parents. The mother is the primary caregiver of infants in most families. I don't think SIDS is usually due to genetic causes. I think these findings highlight a lack in the nurture department. But then, I think that most insanity and substance abuse are reactions to insane circumstances (also mainly not genetic, though a few are).