Broc Brown, a 19-year-old from Michigan, United States, and currently measures 7ft 8ins. Broc was the official Guinness World Record holder for tallest teenager in the world before he turned 19, becoming too old to qualify for the record. Broc has a genetic disorder called cerebral gigantism, and he’s on course to become the world’s tallest man, as he’s growing at a rate of 6 inches per year.