FreeBSD is literally based directly off of AT&T Unix versions 5, 6, and 7 (in varying capacities). AT&T Unix -> BSD -> FreeBSD -> NeXTSTEP -> macOS. (This is o

FreeBSD is literally based directly off of AT&T Unix versions 5, 6, and 7 (in varying capacities). AT&T Unix -> BSD -> FreeBSD -> NeXTSTEP -> macOS. (This is overly simplified, as everything is a mess and macOS contains code from both FreeBSD and original BSD which FreeBSD was based on, among other places.) macOS is ironically a more authentic Unix than Linux is, Linux having been a clone while macOS being a great grandchild. Diagram of Unix History: https://upload.wikimedia.org/wikipedia/commons/7/77/Unix_history-simple.svg https://upload.wikimedia.org/wikipedia/commons/7/77/Unix_his...