When you are born, your body contains all the information it will need to make you grow. Your body even knows how tall you will eventually become. How fast you grow depends on several things.
Taller parents have taller kids, shorter parents have shorter kids.
Even so, you and your brothers and sisters will probably all be different heights when you are grown up. In order to reach your full height, your body needs several things. It needs hormones, which circulate in your blood and tell the bones to grow. You also need good food, good health, exercise, and regular check-ups. In some countries, people do not get enough to eat and they cannot grow properly.