St. Catherine of Siena was born during the outbreak of the plague in Siena, Italy on March 25, 1347. She was the 25th child born to her mother, although half of her brothers and sisters did not survive childhood. Catherine herself was a twin, but her sister did not survive infancy. Her mother was 40 when she was born. Her father was a cloth dyer.
At the age of 16, Catherine's sister, Bonaventura, died, leaving her husband as a widower. Catherine's parents proposed that he marry Catherine as a replacement, but Catherine opposed this. She began fasting and cut her hair short to mar her appearance.