The ER star made the startling discovery about her family's seedy past after signing up to explore her ancestry on U.K. series Who Do You Think You Are?
Kingston assumed her great great great great grandmother Elizabeth Braham made ends meet by renting out rooms after reading a census which listed her profession as a lodging housekeeper.
However, she was shocked to learn that Braham was actually in charge of a house of ill repute, where men paid for sex, in the Westminster area of London.
Kinston says, "When I heard she took in lodgers I thought it was like my nan. But the difference is the lodging Elizabeth established was a brothel. This afternoon I found my inner whore. I was not expecting that."
Branham, a single mother of four, also ran a brothel near the British capital's Leicester Square.
Kingston adds, "She was a force of nature."