Marina Gamba was born around 1570 in Venice. It was here perhaps that she met Galileo, who often visited there during his time in Padua. From their relation three children were born, of whom Galileo did not recognize paternity. Only Vincenzo was subsequently legitimized, in 1619 by intercession of the Grand Duke of Tuscany.

Following are excerpts from their respective baptismal certificates:

"Virginia, daughter of Marina of Venice, born out of wedlock on August 13th, was baptized by me Giovanni Viola."
"Livia Antonia, daughter of Mistress Marina of Antonio Gamba and of …[sic], was baptized by me Clemente Tisato, rector of San Lorenzo."
"Vincenzo Andrea, son of Mistress Marina daughter of Andrea Gamba, father unknown, was baptized by me Father Angelo."

Probably Galileo's position as university professor and his many friendships among the Venetian nobility made it unwise for him to figure officially as the father of the three children. Despite this choice, the whole family lived together at their home in Padua. The sentimental relationship between Marina Gamba and Galileo ceased when he moved back to Florence in 1610. Mistakenly confused with Marina Bartoluzzi, in whose care Galileo had placed little Vincenzo while he was getting settled in Florence, resorting to the sale of a lute to pay for her services, Marina Gamba was long believed to have remarried a certain Giovanni Bartoluzzi. It has been ascertained instead that they were two different persons. Marina Gamba is probably the "Venetian Marina, 42 years of age" who was said to have died on August 21, 1612 "in the parish of San Daniele" (the same to which Marcantonio Mazzoleni belonged, the instrument-maker who lived for a long time in Galileo's home) in a document of the Health Office of Padua. In his request for the legitimization of his son Vincenzo in 1619, Galileo declared that the mother, Marina, at the time of their cohabitation, "had never been married" and was "already dead" at the drawing up of the act. Clearly Marina Bartoluzzi was entrusted with the care of the twelve-year-old Vincenzo, who had lost his mother, until Galileo could bring him to Florence.