I don't know if I necessarily agree with the assessments on ball weight here. The 10% of body weight thing is actually bugging me the most. There's no way I'd set a new bowler who weighs 160 pounds up with a 16 pound ball. There's also no way I'd set a 15 year old who weighs 100 pounds up with a 10 pound ball. 95% of the pros on tour use 15's, and these are guys who have developed the muscles and exercise them daily, guys like Wes Malott who weighs 275+. My daughter is 17, she weighs 100-105, and she uses a 15 quite comfortably. Got 12 year old kids bowling youth leagues who weigh 80 pounds using 14's and zinging them down there, and I also have 60 year old guys who weigh over 225 throwing 14's. It's about what the bowler can handle, body weight has absolutely nothing to do with it.
However, judging by the tone of the post, and more the vocabulary, I would guess this person is at the very least in high school, and is most likely male, so I feel comfortable saying 12 pounds is way too light. May not make the jump all the way to 15, but I would suggest at least going to 14, pending the relevant information requested (age, gender). Also, do a little research before you pick a pro shop to visit, PLEASE don't listen to friends or buddies, if you have a 150 average buddy that says a certain pro shop is great and knows exactly what they're doing, I'd consider that information suspect. A correct fit is super important, and I wouldn't consider myself a fit expert, but I've actually written a pro shop seminar with a heavy emphasis on fit, and I've had a lot of success stories. I can pm you with some information if you would like, but if you can find a good pro shop, they should be able to get you going just fine.
