Much of it is genetic if you look at how different bodytypes present in bodybuilding comps. But they nearly all have some kinda bootay happening even if it comes with massive quads - Heavy squats, sumo squats, lunges etc - I find swiss ball pikes, while they mostly rock the core, give me butt burn and don't use the legs much. Ballet dancers have some of the best butts from all the squating and leaping, though again some have way bigger quads than others, try plyometric workouts and yoga to approximate a ballet class? Goodluck!
Mine has shrunk and needs work