Sean became the all-time leader in individual medals at the IBU Youth/Junior World Championships in 2016, winning three medals to bring his career total to 10. He was the youngest member of the 2014 U.S. Olympic Biathlon Team at the age of 18. The Center Conway, N.H., native had a breakout season in 2013 winning a gold and two silver medals in the IBU Junior World Championships, the first U.S. Biathlon athlete to triple podium at any World Championship event. He would go on to do it again at the 2014 Youth World Championships (2 gold, 1 silver) and 2016 Junior World Championships (1 gold, 1 silver, 1 bronze). Sean was also a member of the 2012 U.S. Youth Olympic Games squad competing in Innsbruck, Austria, where he won a bronze as a member of the mixed relay team.