It isn’t just like you can turn to your sister and tell her that you want to have sex. No, it doesn’t work like that. But then again, if the ice is broken in that area, you can pretty much sleep with her if you want to. I came from a close family.

My parents, before they split up, taught me and my sister that we’d always have each other. So we didn’t fight and we always could talk about anything. Heather is only a year younger than me, and when we introduced sex into the equation, it made us even closer.

Heather and I are older now, and we’ve...