Board Thread:Warhammer 40k General Discussion/@comment-7699236-20150618150629/@comment-2253300-20150622000930

It is right. This isn't speculation, the "No Female Marines" rule is an established fact of the lore. Saying otherwise would be like saying that Orks breed through spores is speculation. The only way it would become possible is if GW decided to alter the established lore of the series to make it so. Mind you if one of the missing Primarch was somehow female then maybe it would make sense, but sadly that's a moot point since GW will never expand on them. Keeping them completely mysterious is a marketing ploy which gives fans wiggle room to make their own loyalist or traitor legion, and thus encourage fans to by their products.