Female adeptes custodes not Space marines. Makes little difference in the large picture but it’s possible within the lore to have female custodians as they’re all humans picked at birth and genetically altered/enhanced individually to make the best soldier they could ever be. GW just didn’t mention females being in that order for 30 years apparently lol

Space marines are all male though, have been explicitly stated as being all male repeatedly and even recently with lore backing of the some of the organ implants and genetic modification templates only work on males since they’re based off the primarchs who were all male as sons of the emperor of mankind.

I’ll end with saying that GW has done great with inclusion in recent years, even explicitly telling Nazis to go find another hobby if they don’t like that GW is making warhammer and warhammer 40k for everyone, of all races, genders, and religions. They’ve always had racial representation and some manner of gender representation in the guard and eldar but now they’re expanding and I’m all for it. I have no issues with any of it so long as GW doesn’t just say ignore the last ~40 years of established lore and even recent lore issuances because we would like to sell more models.