What would a sideshow be without a real human giant to crane your neck up to in awe? And while some people get attention from simply being naturally tall or short, there are actually medical conditions that can cause above-average heights. Gigantism can be a symptom of other conditions, but by and large it's caused by adenoma. That's a tumor of the pituitary gland that causes an excessive amount of growth hormone, which leads to gigantism [source: UCLA]. Obviously, gigantism causes an increase in height, but there are also less noticeable symptoms. Muscles and organs can be larger than normal, and males may have unusually deep voices.
Edouard Beaupre was a Quebecois performer who toured with several circuses. He was 7 feet (213 centimeters) tall at the age of 17 and 8 feet, 3 inches (251 centimeters) tall by the time of his unfortunate early death at 23 [source: Pednaud]. Indeed, an autopsy showed that Beaupre had a tumor on his pituitary gland that contributed to his height.