Parts of it are. The kernel is derived from a Mach microkernel (an experimental kernel in the 80s, which was theoretically supposed to allow different OS personalities to coexist in the same system, sharing resources; macOS’ Darwin/XNU kernel doesn’t implement this capability in full, but you do get the Mach Ports interprocess communication mechanism, and a BSD UNIX personality permanently attached).
Also, macOS is derived from FreeBSD.
It’s derived from BSD 4.3, which predates and is one of the ancestors of FreeBSD
Parts of it are. The kernel is derived from a Mach microkernel (an experimental kernel in the 80s, which was theoretically supposed to allow different OS personalities to coexist in the same system, sharing resources; macOS’ Darwin/XNU kernel doesn’t implement this capability in full, but you do get the Mach Ports interprocess communication mechanism, and a BSD UNIX personality permanently attached).