Those of us who believe in man-woman marriage sometimes talk about the "slippery slope": If we undo the age-old definition of marriage as the union of one man and one woman, this will lead to consequences that go well beyond the terms of the current debate.

Like three men marrying, or a father marrying his daughter.

Advocates for same-sex marriage say "pshaw" and call us crazy. Or worse. To which we often reply: Just you wait.

Well, that didn't take long.

Yesterday, Salon.com published a piece calling parent-child incest normal.

There's even a new politically-correct moniker for it. Don't say "incest," say "genetic sexual attraction."

And because we live in Alphabet Soup Land, it's best to call it "GSA."

Salon was not first. New York Magazine ran a story last month about the "happy" incestuous relationship between a young woman and her father who say they are engaged to be married.

The website Jezebel has run a similar story, though with an unhappy ending.

The Jezebel story begins, "My biological father wanted to have sex with me from the first moment he laid eyes on me." Natasha Rose Chenier writes, "I imagine that, unless you have experienced genetic sexual attraction yourself, this is going to sound entirely unbelievable. But trust me: it is as real and intense as anything."

She claims that 50% of relatives who meet as adults have GSA.

Natasha Rose's mom is a lesbian and her father, whom she later slept with, left when her mom got pregnant. She calls her mother's "lover" a "patriarchal butch lesbian" and so, she says, she always had a "father figure."

To most of us, this heartbreaking mess explains everything about how such a monstrous thing could occur.

And now for the unhappy ending.

Her feelings changed. "It was literally night and day. At night, the first night, I felt thrilled. I thought, 'There's nothing wrong with this, just cultural norms that are meaningless.' The sexual intensity was nothing like I'd ever felt before. It was like being loved by a parent you never had, and the partner you always wanted, at once."

"And then in the morning, we had [a sex act] again, and that's when I wanted to puke and felt like a criminal. At night I was really into it, but by morning I wanted to die. That's not hyperbole; I really wanted to die."

There is always hope. If the still small voice can reach Natasha Rose, there is always hope.