Tiffany was born in San Francisco, California, in the same hospital as fellow band-mate Jessica Jung. Although both born in California, the two would coincidentally end up attending and graduating from the same high school in Seoul, Korea Kent Foreign School, during their preparations for debut in the same group. Tiffany grew up in Diamond Bar, California, attending South Pointe Middle School and Diamond Bar High School.
Tiffany was scouted whilst performing on stage in her home country. She was invited to audition at the SM Entertainment Starlight Casting System and joined the company on October 2004 in Los Angeles, California at age 15.Despite initial objections from her father, she recalls packing up her former life and moving to South Korea after receiving the permission to do so within three weeks of making the decision.She trained for 3 years and 7 months before debuting.Tiffany is the youngest of three siblings. Her older sister studied anthropology at Berkeley.For much of her early career when approached with the topic of mothers or family, Tiffany would often talk in referral to her father or both parents as a plural; on a radio broadcast she stated that she missed her mother who was far away and she had not seen her in some time.However in late 2009, she confessed for the first time in public that her mother had already passed.She later stated that her mother passed away two years prior to her becoming a trainee, and that she is somewhat distant with her father, all of her immediate family living overseas.In August, 2009 Tiffany was absent from a group filming in order to fly to the US and attend the funeral of her late grandfather.She is fluent English and Korean, and can speak conversational Japanese.