Every kid is different. I was shooting a 12ga at clays at 8. And not just once, but often a brick of 100 rounds in an outing. I'd be all black and blue, but loved it. I started my first year hunting deer with a .44mag, but only because that's what we had available. The second year, I had a .30-06. You've gotta gauge what your kid is ready for. It's certainly true that high recoil can make a kid not want to shoot anymore. Stock fit and proper form are vey important in making a gun shootable
-Jake