Bethune was born on Staten Island, the daughter of Ivy (née Vigder), a Russian-born (Sevastopol, present-day Ukraine) actress who started in the Superman radio series, and later became known for playing "Miss Tuttle" on Father Murphy and "Abigail" on General Hospital.

Bethune's first professional acting role was at age six, with a small part in the off-Broadway play Monday's Heroes, produced by Stella Holt at the Greenwich Mews Theater.

[1] As a child performer, Bethune appeared in the original cast of The Most Happy Fella as well as several American daytime television dramas,[4] including a stint as the first "Robin Lang" on The Guiding Light from May 1956 to April 1958.

[1] Newspaper columnist Dick Kleiner described Bethune's performance in a 1958 television production as a "shatteringly beautiful portrayal of Tennessee Williams' young heroine in This Property Is Condemned.

[1] On February 12, 2012, five days before her 67th birthday, Bethune was killed in an apparent hit and run crash while she was trying to help an injured opossum in Griffith Park, Los Angeles.