The Birds, the Bees, and the Butterflies?

Yesterday I had the following conversation with my seven year-old:

Him: Mom, did you know that kids always turn out like their dads?
Me: Why do you think that?
Him: Well, because. If the dad looks a certain way, then the kids look like that too.
Me: But don't you think you and Caden are a little like me too?
Him: (pausing to think) Well, yeah. I guess so.
Me: Well, the reason you share our characteristics is because you and Caden are half daddy and half mommy.
Him: (pausing again to think) Oh. Well, how did we get that way? (Looking very serious) Oh wait!!! I know! You and daddy were probably like butterflies. They rub their butts together when they mate!
(At this point I'm regretting all we learned about butterflies, and he's still looking at me with a totally serious expression like we talk about this stuff everyday.)
Me: (doing everything humanly possible to stifle my giggles) Well, um....not exactly. Now, what would you like for lunch?

Thankfully that was the end of that.