Pretty much, 99.99% of it comes down to genetics. If you ask most models, how tall their parents are, more then likely, their father and mother are/were pretty tall. My father was very thin his whole life, my mother was not. I have my fathers genes, I am tall and very lean and have almost no body fat.
Luck also plays a huge role in it.
You'd think models starve themselves, never eat anything but fruit and drink water. Now, there are some models who might have a different metabolism then other models, but for the most part. Most models have a very fast working metabolism, where they can eat a lot and never gain weight. For the past two years my diet has changed a lot, right now I am eating a lot of organic foods, no longer do I eat fast food, and never fried, some people can drink soda and live off fried food and Pizza and not gain any weight, that is just how some peoples bodies are, and honestly.... there is not much you can do...
What you can do, is make sure you properly exercise, of course it would be wise to see a professional before you get into any type of fitness program, to make sure your heart, and other organs are healthy. Make sure you are eating a well balanced meal each day, getting healthy foods, and staying away from the junk foods. Diet and proper exercise is key to staying healthy.
I write this, as someone who is a professional, and an actual working model.
---ANSWER:Unfortunately you have very little control over how tall you grow. The most you can do (if you are still growing) is to eat a healthy, wholesome diet rich in the nutrients and vitamins your body needs to grow. This means avoiding severe diets that do not meet your nutritional requirements.
You do have more control over the size of your body. However, getting skinny like a model is mostly determined by your genetics. Skinny like a model implies that you want to have little body fat, little muscle and a delicate bone structure. While you have some control over your body fat percentage and how much muscle you possess, you have no influence on the size of your bones and joints.What you can do:
Get your body fat percentage measured to make sure that you maintain a healthy
amount of body fat. Too little body fat can be just as bad for you as too much body fat.