The Mexican brewery, Cervecería Modelo, was founded in 1925 by a group of businessmen, including don Pablo Díez Fernández — who became the company's President, CEO and major stockholder — and Felix Aramburuzabala. Felix's son, Pablo Aramburuzabala, the executive vice President of the brewery, died unexpectedly in 1995 of lung cancer at the age of 63. After his death, several groups tried to gain control of his family's share in Modelo — his wife and two daughters bonded together against these groups.

María Asunción Aramburuzabala Larregui — referred to as Marisun by her friends — was born on 2 May 1963 in Mexico City, Mexico to Pablo Aramburuzabala Ocaranza, a Spanish Basque brewer in Mexico, and Lucrecia Larregui González, a Mexican Painter whose Father, José Larregui Iriarte, was a Navarrese miller in Mexico. She is the granddaughter of Félix Aramburuzabala Lazcano-Iturburu, a Spanish Basque immigrant who co-founded the Mexican brewery Grupo Modelo in 1925 with his friend and partner don Pablo Díez Fernández. Her Father was the Executive Vice President of the Grupo Modelo brewery.

In 1982 she married Paulo Patricio Zapata Navarro. They had two children and divorced in 1997.

On 26 February 2005, she married Tony Garza, US ambassador to Mexico, in a small religious ceremony in Mexico City. On 23 April, they had the civil ceremony near Valle de Bravo, west of Mexico City. U.S. First Lady Laura Bush attended. An estimated one-third of the guests were from Texas. The couple divorced in May 2010.