Her mother was Mayor Flores de Guevara, belonged to the local nobility and was distantly related to Isabella I of Castile.
Her father, Juan Gutierrez de la Caballeria was a highly successful merchant and supplier of the Order of Calatrava.
Five of Marina's relatives were members of the city council, and the family's forebears had been long time royal advisors.
Despite their certificate of purity of blood, it's possible that the growing religious tensions limited Marina's options to marry within her own city.
Alonso de Estrada was the illegitimate son of King Ferdinand II and had been raised in the royal court, was of old Christian blood, respected in Ciudad Real, wealthy, and fiercely intelligent.
Marina took charge of the administration of the couple's ever-growing estates and possessions, while her husband traveled to Mexico City in service of the king.
Marina surrounded her household with native women and learned basic Nahuatl in order to interact properly with merchants and neighbors.
She fought several litigations in court, both for control of her husband's assets and for the right to bury him in the manner she considered proper for his rank.
The Spanish crown audited the accounting books of their secretaries yearly, in search of discrepancies or irregularities that needed punishment.
In Alonso's absence it fell on his widow to provide explanations and reconcile the reports of all New Spain, which she successfully managed to do.
One of them she married close to the Mendoza family, powerful thanks to Antonio de Mendoza´s influence, and no friends of Hernán Cortés, to help her pursue her claims.
After several years she was granted an exception to the Spanish anti-slavery law and permission to own two slaves, a special privilege her husband and other first-line-conquerors had enjoyed.