i dont have kids so i dont know it seems negligent to me the worst i have seen is trying to put dogs and cats on vegan diets this is particularly bad for cats i see it as animal abuse they are pure predators(cats in particular) and there health will suffer as a result. i dont care what people do for the most part with there bodies but some take it a step too far i think. at that age dietary protein is key look at average height beetween n.koreans and s.koreans same genes also the chinese and indians height in america compared to in there native lands. this has to do with animal protein availability. mostly sedentary people could survive as vegans just fine i suppose muscle tissue and hormone levels would suffer as a result maybe you would live longer i would rather be fit strong and die 5 years early and have good quality of life up until then but then again look at all the centarians (i think thats the word for people who lived past a hundred).i have read about them and many of there various lifestyles are totally random in diet activity etc... there seems to be no particular diet or lifestyle which throughly outdoes another. so i think you have to find what works for you as an individual. athletes and growing children need a daily supply of a truelly complete protein for proper function and growth in my educated oppinion