You don't know that. I would argue exactly the opposite. Because they were "swingers" (whoring around might be a better word for it), they are exposing themselves and their children to huge risks. They get drunk/stoned and pick up barflies, then bring them home with them. Aside from sexually transmitted diseases, they should worry about perverts, serial killers, home robbery (excellent casing opportunity, after all) and any number of vile things. Despite claims to the contrary, child molesters often use a parent, usually the mother, as the quickest route to the child.