Exactly how does an author make something like incest seem so real?

That, kiddies, is known as a negative campaign tactic. If Citizen Webb was black, I'd be deported.

If he was a lesbian, he'd win a Pulitzer.

Washington's other newspaper: Allen Blasts Webb Novels For Sex Scenes
Virginia Sen. George Allen (R) has accused his Democratic opponent, James Webb, of writing inappropriate sex scenes and demeaning descriptions of women in his fictional books, the latest character attack in a close and nasty campaign.

The Washington Times: Webb defends sexual explicitness of his novels
Virginia U.S. Senate candidate James H. Webb Jr. said yesterday that incumbent Sen. George Allen crossed the line when he used salacious excerpts from his wartime novels to question his character and respect for women.