The Time Travelling Pro-Incest Loophole

The Professor didn't consider there was anything wrong with using his prototype time-machine to travel back to 1964 in order to have sex with his own mother (she'd been quite the cutie).

He figured he could get around the laws against incest by arguing that, in 1964, he didn't exist, so no link between them would be found. As his current self was 35-years-old, there could be no allegations of under age sex taking place.

He cackled and rubbed his hands with glee. He had it all mapped out. He'd finally make his ultimate fantasy come true.