He might start eating meat eventually when he grow up. I don't always follow my parents rule or tradition when I grow up.
There is a certain amount of cognitive dissonance that is necessary to eat meat without feelings of guilt or disgust, and at the same time feel compassionate when animals of other species are hurt or killed. Once people become vegetarian, whatever the reason, they often lose that ability.
I know a few people who grew up vegetarian and never had the choice as a child. Because they never learned the difference between 'pig' and 'pork', 'cow' and 'beef', 'calf' and 'veal', it's often harder for them to make a conscious decision to start eating meat.