An illegitimate daughter of Emperor Charles V and Johanna Maria van der Gheynst, a servant of Charles de Lalaing, Seigneur de Montigny, she was brought up in Brussels by the family Douwrin. She was taught to speak French, Italian and Spanish but was unable to speak Flemish. 
In 1529, aged only seven, she was engaged to Alessandro de' Medici, a nephew of the Pope. In 1533, after having been acknowledged by her father, she was allowed to call herself Margarete of Austria. 
On 29 February 1536, aged fourteen, she married the almost thirty-
year-old Alessandro. However, a year later she became a widow when he, 
hated for his extravagances, was murdered. Margarete withdrew to Prato, a few miles from Milan. To please Pope Paul III, at sixteen years of age she became engaged to his grandson, Ottavio Farnese, who was only thirteen, and became Marquess of Novara. 
In October 1538 she went to Rome for her nuptials and, still dressed in mourning, was presented to the Pope. It seemed omninous when, at her wedding on 4 November 1538 with the exchange of rings, she failed to say 'yes'. Even though her second marriage was as unhappy as her first, in 1545 she gave birth to twins; however only one, Alexander, survived. 
In 1547 her husband inherited the Duchies of Parma and Piacenza. In May 1559 her half-brother, Philip II, King of Spain, placed her in charge of The Netherlands. This appointment was meant for only seventeen months but she stayed in charge for nine years. She was never appreciated but resented as the daughter of a servant as well as for her devoutness and her Spanish secretary. Margarete was in an impossible position when Philip II placed a Spanish garrison in Piacenza and took her son to Spain.

Source: Leo van de Pas