Agree with @Overo Mare that big combs & wattles at that age mean "boy," even if one of them isn't sporting fancy plumage yet.
We're currently raising selectively bred Marans from a breeder as well. They're 10 weeks. 2/5 are cockerels, and you can really see the difference. Here are photos as they started to settle into post-breakfast naps this a.m. The pullets look like the girls in the background of your photos: small combs, not much wattle.
We're currently raising selectively bred Marans from a breeder as well. They're 10 weeks. 2/5 are cockerels, and you can really see the difference. Here are photos as they started to settle into post-breakfast naps this a.m. The pullets look like the girls in the background of your photos: small combs, not much wattle.