Board Thread:Warhammer 40k General Discussion/@comment-91.224.27.226-20131031140001/@comment-18016240-20140102092718

Again, chapters.

If you have a son or daughter (whatever your gender is) would you expect them to look exactly like you? Same facial features, body type, hair and eye color, etc? Likely not, each generation from you is likely to look more and more different, and if the missing legions look roughly like the Ultramarines with a few quirks it'd be easy enough to integrate them into their legion after a few generations.