Is it possible for fraternal twins to have different fathers?

Not only is it possible for fraternal twins to have different fathers, it has actually happened. There's even a medical term for it: superfecundation. The classic case, which is discussed in Williams Obstetrics (1980), was recorded in 1810 by John Archer, the first doctor to receive a medical degree in the United States. According to Archer, a white woman who had sex with a black man and a white man within a short time subsequently gave birth to twins--one white, one mulatto. Other cases have been reported since.