The average newborn infant is about fifty centimeters long. In 20 years, the little body becomes more than triples in length. The average height of a man is 1.7 meters.
But a man doesn’t stop growing then. He actually continues to grow even after the age of twenty and continues to grow further till the age of thirty-five or in some cases forty also.

Do you know what happens after that? The man doesn’t stop growing but he begins to shrink after that. The average person shrinks as much as ten millimeters every ten years after the age of forty. The reason is due to the shrinkage or drying up of the cartilage in the joints and the spinal column.
Growth varies with the seasons. Children grow more rapidly during the summer than during the winter. Children of school age actually grow twice as fast during the summer months as during the winter. Not only this many other factors are also responsible for the growth of the child. Good environment, better food, healthy living, good exercise are the main factors.
Our growth is determined by four important sets of glands- the thyroid, the pituitary, the thymus, and the sex glands. When these glands operate normally and there is the proper balance between their functions, then growth is normal.