It's always possible to wind up with either. Just like you get certain traits from your mother and certain one's from your father, a chicken can do the same. BUT....what is considered a broody breed is also not always right either. I've seen RIR's go broody(not known for broodiness) and I've seen orpingtons never go broody(suppose to be a broody chicken). It's all in the bloodlines, I'd guess.
well i don't have any chickens that really lay on my eggs but my rooster and one of my ducks and she has went broody for the last week and while she is laying every once in a while my largest astralorp will lay with her their are about 20 eggs underneath her but i doubt even 40% will hatch
i have a question though will she move at all while broody?