Boylen's mother was the late Javanese-born Canadian dancer, Willy Blok Hanson and her father was an Australian soldier.

[1] Born in present-day Indonesia in 1947, she moved with her family to Toronto, Ontario, Canada, in 1951.

[1] She earned individual gold medals at the 1971, 1975 and 1987 Pan American Games, making her the only athlete to achieve three individual gold medals in Pan Am history.

[2] At the Summer Olympics, her best performance was in 1976, when she came seventh in the individual competition[3] and fifth in the team event.

[4] She was also the highest placed North American rider at the 1984 Olympics in the individual dressage when she came tenth.