Born in 1995 in Seoul, South Korea, Yang took up golf when she was six years old. She spent time in Thailand during her childhood and speaks fluent Thai. At the age of nine she moved to Mesa, Arizona. By that time she had won 20 junior tournaments, including the 2002 UBC Junior World Golf Tour title at the age of seven. At age 12 she began playing American Junior Golf Association tournaments. She won the Randy Smith Classic in Lubbock, Texas in her third AJGA start, becoming the second youngest winner of an AJGA event. In 2007 she won the US Kids World Championship and was named to the Rolex Junior All-American team that year. She was awarded that honour in 2008. At age 14 she moved to Scotland and continued her winning ways, with victories in the Welsh Ladies Open Stroke Play Championship, the Danish International Ladies Amateur Championship, and the English Women's Open Stroke Play Championship. She moved back to the US in 2011 and won the Women's Trans National Amateur Championship, becoming the youngest winner of the event.