It's funny that you mention FreeBSD, because large portions of FreeBSD were incorporated into Mac OS X. If you look through the Mac OS X man pages you'll find references to various BSDs, mostly BSD and FreeBSD.
walrus01
Of course, but not to the extent that they took a freebsd base (vs NeXT) and put an osx GUI on top of it. When I first used osx from a command line at v10.4 and saw macports, the freebsd heritage was obvious.