Jessica was born in San Francisco, California in the same hospital as her fellow Girls' Generation member, Tiffany. While on vacation in Korea, she and her sister were scouted in a shopping mall by S.M Entertainment and joined the company in 2000.[1] She trained for seven years as a trainee before debuting as part of the Korean girl group Girls' Generation.
Her younger sister, Krystal, is a member of the Korean girl group f(x). They are both currently active in their groups, being signed under S.M. Entertainment.