Duncan grew up in Fort Lauderdale, Florida and attended American Heritage School. She started playing golf at the age of 9 and had a successful amateur and college career, reaching the semi-finals in the 2006 U.S. Women's Amateur at the age of 15.[2] In 2009, the same year she graduated high school, she qualified for the U.S. Women's Open, and advanced to match play at the U.S. Women's Amateur for the fourth straight year, placing fifth in stroke-play qualifying.[3]
Duncan played collegiate golf at Duke University from 2009 to 2013 where she was a four-time first team All-American, recorded six wins, and was named 2010 ACC Rookie of the Year. She was named ACC Player of the Year in 2010, 2011 and 2012, and also NGCA National Player of the Year in 2012.[4]
Duncan turned professional in June 2013 after graduating and joined the Symetra Tour, where she recorded three top-10 finishes in seven events in her rookie season. She finished tied 15th in the 2013 U.S. Women's Open. Duncan earned conditional status for the 2014 LPGA Tour at Q-School but only played one event. In 2015, she was runner-up at the FireKeepers Casino Hotel Championship and finished tied 15th at the Final LPGA Qualifying Tournament and joined the LPGA Tour full-time for the 2016 season.
In 2017, Duncan recorded the first two top-10 finishes of her LPGA Tour career, including a fourth place at the Manulife LPGA Classic. In 2018, she had her best LPGA season to date, recording three top-10s, including a runner-up finish at the Volunteers of America LPGA Texas Classic, where she birdied her final three holes for a 64, the low round of the tournament, but Park Sung-hyun chipped in on the final hole to win.[7] Duncan finished 42nd on the money list after also making some of her best major appearances, finishing tied 15th at the KPMG Women's PGA Championship and tied 22nd at The Evian Championship.[8]
