Some children get to eat lots of food that makes them grow.
This kind of teasing is the worst. Hello, curious kids! Only your identical twin has the same DNA as you. To borrow a comparison from Leonard Hayflick, a cell biologist at the University of California, San Francisco UCSFthe body is rather like one of the Mars fly-by probes, but engineered to reproduce, not reconnoitre.
That means, for example, that traits which are advantageous in early life are favoured, even though they may cause later harm. From an evolutionary viewpoint, once our genes have orchestrated the growth and development of the body to the point that it can reproduce, the purpose for growth is complete.
Some diseases may make you grow less. Francis Galton was one of the first scientists to do some tests to work out why this was the case. It is the high concentration of estrogen in the blood that causes the growth plates of our bones to fuse.
But some cells, such as cancerous ones, keep going on and on.
At this point our genetic program tells us to stop growing. On the plus side, sitting higher makes it easier to see and might help if you get carsick and need to keep looking out the window.
Occasionally, though, doctors will give hormone treatment — usually testosterone — to guys with constitutional growth delay who are having a rough time waiting for puberty to kick in.