(1) You're thinking of FreeBSD. Not OpenBSD. A lot of the command line utilities Unix nerds would use in the terminal are ported from FreeBSD.
(2) The kernel, Darwin, is NOT based on FreeBSD. Darwin is a direct descendant of NextStep, based on the Mach microkernel.
(3) And pretty much all of the GUI and indeed the whole Cocoa API are also from Apple/Next. Not FreeBSD. Essentially, everything that isn't what Unix nerds interact with? That's pretty much all Apple. (Except for Apache if they turn on personal web serving, but that's not FreeBSD. And Webkit started as a fork of KHTML, but, y'know, not FreeBSD again.)
(4) For that matter, even a fair amount of the Unix nerd stuff is specific to OS X, like launchd, or has tweaks to support OS X-specific nerdosity.
So, vain hope, could we _please_ knock this sort of nonsense off? For both better and worse, OS X is very much its own animal, and whether or not you like it, it's ridiculous to claim that Apple doesn't put a hell of a lot of development work into it.
(2) The kernel, Darwin, is NOT based on FreeBSD. Darwin is a direct descendant of NextStep, based on the Mach microkernel.
Darwin[1] is not the kernel, is the operating system. The kernel is called XNU[2] which was a combitation of a non microkernel version of Match with the 4.3BSD unix kernel interface. Apple remplaced the 4.3 BSD code with FreeBSD code[3].
(2) the Mach kernel was originally developed for BSD.
(3) true, they did make a shiny wimp variant.
(4) is that why stuff like rename is not there? The man page for rename is there, but rename isn't for some reason though. I had to rename lots of things and I had to write a script and everything.
Most of the development was already done for them in the development of Open-BSD.