Not really comprehending

I guess it's because Mike is still only 7. We're on winter break now and Mike is attending a kids' club (US = VBS) at a local church. They are using a pre-packaged deal and it involves Answers in Genesis material. Mike and I had the following conversation this afternoon after the morning's fun:

Mike: Mum, do we have a family tree?

Me: Of course we do.

Mike: What is it?

Me: Well, I'm your Mummy and Daddy is your Daddy and then...

Mike: No, I don't mean that. Do we have a family tree?

Thus followed more patient attempts to explain what a family tree is with no success. Sometime later:

Mike: Do we have a family tree?

Me (*exasperated*): We have a Jacaranda tree in our backyard. Is that what you are thinking of?

Mike: *Yes*

Me: I don't think that's what the kids' club means.

Mike (*sings*): There's no monkey in our family tree.

I wonder if we should remind him about the possum. I'm just wondering what the leaders would think tomorrow morning when Mike rolls up and tells them there's a possum in our family tree.