Natasha Lyonne was 6 in Heartburn when she played the character 'Rachel's Niece (uncredited)'.
That was over 38 years ago in 1986.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 45, and has starred in 82 movies in total, 82 of those since Heartburn was released.
In Heartburn, I think Natasha Lyonne looks: