Wrong. The sickos are the people who raise their children to fear their sexual urges,and to think that they will burn in a pit of fire forever for merely having desires. It's the sexaully repressed/obsessed who are twisted,and they twist their children as a part of their natural being.
I've known several couples who were swingers,and their children all grew up to be responsible and successful adults.
That's just as moronic a statement as saying that swingers can't be loving parents. I happen to know many couples who you would consider twisted and all their children grew up to have healthy sex lives and not get divorced, either. What you think of as teaching children to "fear" their sexual urges is really teaching them to "control" them. You don't have to scratch every itch, believe it or not, just like you don't have to feed your face every time you think of food. There's a happy balance between The Scarlet Letter and Bob & Carol & Ted & Alice.
Back to the main subject, though, it remains to be seen whether or not Danielle's parents' lifestyle is incidental to her disappearance or not. It may have a lot to do with it, or it may have nothing to do with it. If it was someone outside the home who took her, and that someone knew that the parents' attentions were, shall we say, diverted at the time of the abduction, then their lifestyle choice is fair game, in my opinion. It's not something you can keep secret, and if the parents haven't been honest about their actions on the night in question, when the stakes are so high (their little girl's life), it's my natural urge to suspect the parents of, at the very least, worrying more about their lifestyle being exposed instead of their daughter's life, and I know you think it's healthy to indulge our urges.
Of course, they could have been completely honest with the police and the police could have been trying to "clean up" the parents' alibi for public consumption and not done a very good job of it.