[jebblue]

In addition to UNIXgod's comment, I can refer you to:

http://en.wikipedia.org/wiki/OS_X

There you will find:

http://en.wikipedia.org/wiki/Comparison_of_BSD_operating_sys...

"... Apple Inc.'s iOS and Mac OS X, with its Darwin base including a large amount of code derived from FreeBSD."

http://en.wikipedia.org/wiki/Darwin_(operating_system)

"Darwin is an open source POSIX-compliant computer operating system released by Apple Inc. in 2000."

[jeremyjh]

Yes, Apple has used free BSD code to build an OS that is not open source. I don't think anyone would dispute that.