Board Thread:General Discussion/@comment-31102210-20170727030106/@comment-29800728-20170731143642

You're right by saying they were volunteers but their parents had still died. Anyway, Episode 18 of Season 15 adds more to Red vs Blue and Halo being seperate.

In Halo the UNSC HQ is in Sydney, Austrailia. In Season 15 Episode 18 it is in Wyoming, America. So that is a massive piece of proof that they are seperate.