Conversation so far:
Where was Christina Aguilera born?
New York City, New York.
How long did she live in NYC?
Her family moved frequently because of her father's military service.
When did she begin singing?
Growing up, Aguilera, known locally as "the little girl with the big voice", aspired to be a singer, singing in local talent shows and competitions.

Question: When did she become famous?
Self-contained rewrite: When did Christina Aguilera become famous?