
To Anonymous Coward
In Mac OS X, drop to a command prompt/console, cd to /var/logs and cat messages,
Check the Kernel load up messages and compare it to say.. Ubuntu
Every command you typed, the layout of the filesystem, the "Kernel" are all the same as Linux, which of course is a clone of Unix.
The company jobs created the OS X GUI in, was called NeXT Software.. not so strangely NeXTs homepage now goes to apple.com
Also, look up the XNU Kernel, and its references to BSD... which is, oh you guessed it, a flavour of Unix.