Bonny's father William Cormac first moved to London to get away from his wife's family, and he began dressing his daughter as a boy and calling her "Andy". When Cormac's wife discovered William had taken in the illegitimate daughter and was bringing the child up to be a lawyer's clerk and dressing her as a boy, she stopped giving him an allowance. Cormac then moved to the Province of Carolina, taking along his former serving girl, the mother of Bonny. Bonny's father abandoned the original "Mc" prefix of their family name to blend more easily into the Charles Town citizenry. At first, the family had a rough start in their new home, but Cormac's knowledge of law and ability to buy and sell goods soon financed a townhouse and eventually a plantation just out of town. Bonny's mother died when she was 12. Her father attempted to establish himself as an attorney but did not do well. Eventually, he joined the more profitable merchant business and accumulated a substantial fortune.