I can speak for myself. I became vegetarian at 13 after probably six or more years of arguing with my parents about it. I just had, like the OP's kiddo, a visceral reaction to killing animals for food. I wasn't able to differentiate btwn my dogs and cows in terms of why I'd feel okay eating one and not the other. My parents tried to force me to eat meat up until I was 13 which led to huge battles at the dinner table with me crying and being told that I couldn't leave the table until I ate the meat. I'd sit at the table literally for hours crying until they gave in. I'd also slip hamburger patties out of the bun and feed them to the dog and just eat the bun pretending that there was still a hamburger in there. At 13, my mom told me to just cook my own food.

At 16 I went vegan and have been vegan since. Both of my kids are also vegan. They ate a strict o/l vegetarian diet for part of their childhoods as a compromise with my omni dh and we let them decide when they started asking questions. They both went vegan in the past two years. Dd14 was vegan for the first two years as well b/c dad was living and working out of state during that time and I wasn't going to feed her things I wasn't eating. I am also Buddhist, although I wasn't raised Buddhist, and, for me, my dietary choices are an aspect of that belief system.

Study Strategies for Accelerated Learners