Margaret was born of farming parents, in Laviano, a little town in the diocese of Chiusi. At the age of seven, Margaret's mother died and her father remarried. Stepmother and stepdaughter did not like each other. As she grew older, Margaret became more willful and reckless, and her reputation in the town suffered. At the age of 17 she met a young man, according to some accounts, the son of Gugliemo di Pecora, lord of Valiano, and she ran away with him. Soon Margaret found herself installed in the castle, not as her master's wife, for convention would never allow that, but as his mistress, which was more easily condoned. For ten years, she lived with him near Montepulciano and bore him a son.