My Dad, who started me hunting and shooting, was not and still isn't a muzzleloading enthusiast. He sure got me into hunting tho! I started with a BB gun, then 22, tried shotguns but preferred the prescision of rifles, got into muzzleloaders 30 years ago because of an interest in history and old things in general. I still shoot centerfire but it's almost always a BPC rifle of some kind.
My two sons were started much the same as me. The youngest has no interest in hunting or shooting. The oldest still hunts but much prefers centerfires altho he is deadly with his 50 cal. CVA Mountain rifle. He just hates the clean-up. He's also much more into long bows and making arrows than shooting any kind of firearm.
I think what brings youngsters into hunting is wanting to do what "grown-ups" do. Whether that be Dad, an uncle, grandpa or reatives who hunt of their friends. It's outside, it's rifles and pistols and shotguns, it's bringing home the meat, it's high adventure for a 5-10 year old. It's the hunting that brings kids in, the choice of firearm is probably dictated by what their mentor uses. When my boys were young we hunted all three seasons with all three weapons, centerfire, muzzleloader and bow. I still do but as I said my centerfire is still black powder and cast bullets and bow season is long bows and Port Orford cedar arrows.
Vic