Heteropaternal superfecundation is common in animals such as cats and dogs. Stray dogs often produce litters in which every puppy has a different father.
Though rare in humans, many cases have been documented. In 1810, American physician John Archer documented a case in which a white woman gave birth to mixed twins one white, one mixed-race after having sex with a black man and a white man within a short time. In 1994 a woman gave birth to twin girls named Skylar and Ariana who have different fathers. In June 2008, a Texas woman gave birth to fraternal twins fathered by different men. In that case, a DNA test concluded that there was a 99.999 percent chance that the twins had different fathers. The twins’ mother acknowledged having had intercourse with more than one man in a short period of time close to the conception date.