As I mentioned in my post. Steve left Apple, started NeXT, which built NeXTSTEP off of a modified Mach 3.0 microkernel. Apple acquired rights to NeXT when the company folded.
Ok, so Apple wrote a (relatively small) portion of OS-X. I already admitted that. Pretty much "theirs" only by rights, not by development. But anyway...
Microsoft did the whole UNIX, thing, too. Way before OS-X. Way before Windows, even. Microsoft XENIX.
Further UNIX doesn't really mean anything anymore. There was a time when UNIX was actually the NAME of an Operating System. Now it's a certification that is given to Operating Systems whose companies pay lots of money to have tested to conform to UNIX standards by the company that owns the UNIX trademark. It's meaningless. An Operating System doesn't even have to be based off some original ATT UNIX code to be UNIX. As I mentioned, NT could be certified UNIX, that POSIX subsystem and what not.
And, given that UNIX doesn't actually mean anything anymore, what's so great about UNIX? It's an antiquated, outdated model of computing, it's from the 60s! (Yes, I'm aware NT goes back about as far.) Nothing UNIX does is new, or revolutionary, as much as the OS-X and GNU/Linux fanboys wants it to be so. Plan9, by Bell Labs, now that is a modern, well thought-out OS design. Avoids a lot of mistakes UNIX made, and continues to make.
But, alas, my only point here is that OS-X is not necessarily better than NT, and is certainly no better just because it's UNIX branded. You want to blame NT problems on someone, like I said, ***** at 3rd party developers, not MS.
Off my soapbox now