We're pretty close to finding out the truth that John's grandpa hid away... a couple more strips and this arc will finally be able to be understood. It's intentionally ambiguous due to the type of arc it is. 

I wanted to have Zoey in this since she's taking college courses in biology and it made the most sense to me that she'd be the one to make connections. Also she's in the place where they've brought boxes upon boxes of stuff so she'd be interested in seeing what's in them. I'm sure she started to understand that it's something she has an interest in and that kept her digging through them.

Also George wouldn't have the attention span to be the one to go through boxes with John.