Allen was born in 1995 in Jacksonville, Florida. In high school at Providence School of Jacksonville, he graduated cum laude, helping lead the team to a 90-10 record with one state title and two state semifinal appearances. In 2014, he was named a McDonald's All-American and won the slam dunk contest at the Powerade Jam Fest. He was also selected for the 2014 Jordan Brand Classic. Allen was named a First Coast All-Star Scholar-Athlete in 2014. At Duke, he was one of only three graduates to receive All-ACC Academic honors all four years, joining Quin Synder and Amile Jefferson. Learn more about Allen on Twitter and Instagram (@graysonjallen).