Where did OpenBSD come from?

[Lucas Czejgis]

Hello!
I have a little question, and I'm quite confused. I know, that first, was 
386/BSD released, then came FreeBSD and NetBSD. But which *BSD gave "birth" 
to OpenBSD.
In a book called "FreeBSD: The Complete Reference" the author says, that 
OpenBSD came out from FreeBSD.
But, on this 
(http://www.over-yonder.net/~fullermd/rants/bsd4linux/bsd4linux2.php), the 
author says: "Later on down the road, some internal disagreements within the 
NetBSD project caused the OpenBSD project to split off from it."
And now I don't know where OpenBSD came from? FreeBSD or NetBSD?

Lucas