Google is your friend. The connection is surprisingly not close at all and goes back to the 70’s.
They are both Unix-Like systems, however later Mac OS is now considered a branded version of Unix officially. Sometime in the 70’s, AT&T released its rights to Unix for Academic and other commercial uses. Research Unix was released by Bell labs and from this Berkeley basically rewrote most of that to create what we now know as BSD. Minix and GNU are also derivatives of Bell labs Research Unix. OS-X was started as a commercial derivation of BSD.
Linux was inspired by Minix and GNU however was a complete re write.
They are like distsnt cousins going back to Bell Labs Unix and the first sub licensed unix variants outside of AT&T and Bell Labs.