I don't think that anyone is entirely at ease at the thought of their parents having sex. It's one of those things that disturbs you deeply — though the shock of the epiphany is momentary, there's a lingering aftertaste. That gut-full-of-eels, whole-body gooseflesh sort of malaise that never entirely subsides. If you've never swallowed a bad oyster, anyone who has can tell you what its like: the sight, scent, or even the mention of shellfish brings it back again.

It never stops.

You think you'd get over it with age — but the older you get, the older they get, and the less likely you become ever to be able to cope. Reminding yourself that they weren't always so old and leathery can help: around the time of your conception, all the snorting and squealing took place between the two younger, firmer people your parents used to be. That should hold you over for a while, at least until you realize that even though they were younger ...

... they probably looked a lot like this.