He Got it From Whom?

"I Got It From Agnes" is an awesome Tom Lehrer song --- really, is there any other kind? --- complete with a growing network to illustrate what is going on.

This is a different recording of the song than the one I own, but the copy I have on iTunes doesn't have a network diagram to go with it (and that does add to the humor substantially).

(Tip of the cap to Edmund Chattoe-Brown and Stan Wasserman.)