Some more details, to help make the situation crystal clear.
The rumor that Thomas Jefferson had fathered children by his slave Sally Hemings first captured the public's attention in 1802, when muckraking journalist James T. Callender, a former agent of Jefferson's who turned against the president when he refused to offer him a government sinecure, wrote in a Richmond newspaper, "It is well known that the man, whom it delighteth the people to honor, keeps, and for many years has kept, as his concubine, one of his slaves. Her name is SALLY." www.loa.org
Notice that word, "concubine."
From the wikipedia article on sexual slavery: en.wikipedia.org
Sexual slavery and sexual exploitation is attaching the right of ownership over one or more persons with the intent of coercing or otherwise forcing them to engage in sexual activities. This includes forced labor, reducing a person to a servile status (including forced marriage) and sex trafficking persons, such as the sexual trafficking of children.
Sexual slavery may also involve single-owner sexual slavery; ritual slavery, sometimes associated with certain religious practices, such as ritual servitude in Ghana, Togo and Benin; slavery for primarily non-sexual purposes but where non-consensual sexual activity is common; or forced prostitution. Concubinage was a traditional form of sexual slavery in many cultures, in which women spent their lives in sexual servitude. In some cultures, concubines and their children had distinct rights and legitimate social positions.
Notice that "Concubinage was a traditional form of sexual slavery"