Polygamy Averted

My boys told me this morning that they plan to live together when they're grown. In a house with a lab in the basement. With metal walls where they can invent Pokemon and experiments like Stitch. And they're going to have one wife. "Yeah, we're gonna share her!" Walker nodded emphatically. "Um, don't you think that could get a little too complicated?" I asked. West's face fell until I suggested that maybe they could marry sisters. "Yeah, that'll work!" they high-fived and went on their merry way, but I stood there stunned for several minutes, mind-whacked. They are SEVEN and FOUR, for crissakes, but they had clearly worked this out some time before between them? I'm glad that they're close, and I'd throw in an "LOL" here, but it's really more of an OMG!