its apart of genetics and some suffer from being too tall. That is called 'marfan Syndrome'
people get tall because of the jeans of there family like there grandmother might be tall but you mother might be short and your father might be tall too so you are more then likely to become tall I...
Tall people are tall, because of their genetics. Ex: if your mom is tall and your dad is tall then you are most likely going to be tall, too. (:
God only lets people grow until they are perfect. Some of us don't take as long as others!