Can a sense of humor be inherited? Or is it imposed by a family's own cultural context? Or both?

Tonight I offered to snuggle with the kids at lights-out time. Their room is the warmest in the house! It makes both me and James really sleepy when we read to them at night.

Me: Okay, everybody tucked in?
Tuck: Here, mama, you can hold Eva [Wally koala's baby].
Me: That's sweet, Tuck, but I have the two of you on both sides of me! That's as good as it gets, I don't really need a stuffed animal.
Tuck: But I am trying to be nice!
Me: Oh! And it is nice of you! OK, I will be happy to hold Eva, thank you.

[Moment of quiet.]

Emi: I don't have anything to give you, mama. I wish I did.
Me, having a melty parent moment, with images from the 1968 claymation version of The Little Drummer Boy suddenly flashing through my head: Emi honey, that is so sweet! How about just a hug?

[Moment of quiet.]

Emi: How about a GIANT HIPPO! [Body slams me with an IKEA hippo pillow as big as she is.]

[Moment of quiet, followed by uproarious laughter from all three of us.]