Fonseca was born on March 16, 1979, in Veracruz, Veracruz, Mexico. She is the daughter of dentists Hugo Fonseca and Guillermina Castellanos. She has one brother Hugo and one sister Jacqueline. She started her acting career by performing in a local television show.[which?] At 16, she was accepted into the C.E.A. (Centro de Education Artistica) in Mexico. After winning the award in the "El rostro de El Heraldo de México" competition in 1997,[1] she participated in the soap opera La usurpadora. Fonseca had a lead role in the soap opera Rosalinda playing the little sister of Rosalinda, Lucy.[citation needed]