Hi Our body needs proteins for a variety reasons. These proteins are made up of something called as amino acids. Arginine is one type of amino acid. It is perfectly fine to consume Arginine. So don't worry. But, at the same time, tell your son that Arginine alone won't lead to increase in height. Height growth is dependent to a VERY LARGE extent on hereditary factors i.e. whether a person's parents are tall or not. This, alongwith proper nutrition and moderate amount of stretching exercises to a SMALLER extent will lead to increase in height.