How old are they? When you say by their feathers do you mean feather sexing when they are little or the long, pointy hackle and saddle feathers roos get as they mature?
They are not old enough to have saddle/hackle feathers yet...you will be able to see them pretty easily when they do come in...let me see if I can find a good pic to share...
See the long narrow feathers streaming down his neck? Those are his hackle feathers...and the long skinny ones above his tail are his saddle feathers I hope this helps.