[misterrob]

The modern coaching trees:

Walsh and then Sieffert
Parcells
Jimmy Johnson
Holmgren
Billeck

[Vigilantcitizen]

Both Holmgren and Brian Billick come from the Walsh coaching tree.

[discostu]

Parcell's only entree is Belichick though, and given how Belichick is eclipsing Tuna's achievements (especially Tuna's achievements with the other Bill at his side, which are none), I'm not sure he should be thought to have a tree.