As you read this grotesque story, ask yourself a key question, "Why is this wrong?" Hint: There is a very good answer by the way, although it's one liberals will have trouble coming to grips with...

John and Jenny Deaves reunited 30 years after Mr Deaves separated from Jenny's mother.

Jenny was 31 and just two weeks after meeting, father and daughter had sex.

"John and I are in this relationship as consenting adults," Mrs Deaves told the Nine Network's 60 Minutes tonight.

"We are just asking for a little bit of respect and understanding."

Their nine-month-old daughter Celeste, shown on TV, appears fit and healthy.

Mrs Deaves said soon after reuniting with her father she began to see him as a man first and her father second.

"I was looking at him, sort of going, oh, he's not too bad," she said.

"Like you might look at a man across the bar at a nightclub."

Mrs Deaves brought two children, Samantha and Alex, into the relationship after splitting from her former partner.

Mr Deaves admitted that he "initially" thought having sex with his daughter was wrong.

Now, why did I ask, "Why is this wrong?" at the start of this post? Because if you buy into a lot of the silliness that is passed off as a common sense wisdom by the Left, you'd almost be forced to give the thumbs up to this abomination in order to be consistent.

For example, haven't we been told that what goes on in the privacy of the bedroom is none of the government's business? What about: anything that two consenting adults do in the privacy of their own homes should be allowable? Oh, here's a good one: you can't legislate morality.

But, guess what? Sometimes you can and should legislate morality; the government does, on occasion at least, belong in a bedroom -- and, no, anything that two consenting adults want to do to each other shouldn't necessarily be okay.

Could you just say that it's wrong because it's gross? Well, only if, to be morally consistent we're going to start banning everything that's gross. But, does that make sense? There are lots of gross things people can do that aren't illegal. So using "grossness" as an excuse simply doesn't cut it.

What about the fact that birth defects could be caused by incest? That's easily correctable,

Birth defects could be prevented by extending to sibling marriage the rule that five states already apply to cousin marriage: You can do it if you furnish proof of infertility or are presumptively too old to procreate.

So, why should adult incest be illegal?

Simple. The answer is because it's immoral -- and, yes, that requires putting one set of morals above others and making laws based on those morals. That's why adult incest is and should remain illegal. It's also the primary reason why gay marriage, polygamy, bestiality, prostitution, and numerous other ills should remain illegal -- and people should remember that.

Once you torpedo the idea of basing laws, at least in part, on a moral code, you are on your way to opening up a Pandora's box of horrors for society to deal with...