A 19-year-old-boy from the US state of Michigan, Broc Brown, growing at a rate of six inches a year, currently measures 7 feet and 8 inches. Also known as 'gentle giant', he suffers from a genetic disorder known as Sotos Syndrome, or cerebral gigantism. Broc was previously recognised by Guinness as the world's tallest teenager before surpassing the 18-and-below classification.