You mean that operating system based on a UNIX knock-off, chock-full of foreign free software?
Well according to BSD.ORG the O/S that Mac is based on is UNIX. And Apple is a fine US company that invented their product here in the US, and sell it for a profit around the world, without allowing foreigners to make free copies and give it away for nothing. Which is exactly why Linus Torvalds refers to Apple as "a piece of crap".