But why did Robert Wadlow grow up to be so tall? Doctors eventually diagnosed him with hyperplasia of the pituitary gland, a condition that caused rapid and excessive growth due to an abnormally high level of human growth hormones in the body. Even by the time of his death, there was no indication that his growth had ended.

Paille/Flickr The tallest man in the world stands alongside his family, who are all of average height and weight. Doctors eventually diagnosed Robert Wadlow with hyperplasia of the pituitary gland, a condition that caused rapid and excessive growth due to an abnormally high level of human growth hormones in the body.