Twins With Two Different Fathers
A man in Turkey found out he is father to only one of the twins his wife delivered. He suspected his wife had been unfaithful to him with the man she dated prior to marriage. The wife's parents had forced her to marry her husband instead of the man she'd been dating. Because of this fact, the husband decided to have the babies' DNA tested.
As a result of the DNA tests, he has decided to divorce his wife and to disown the twin that is not his biological son. The disowned twin is now a ward of the state. Because the husband and the wife's family made death threats against the new mother, the court has ordered them to stay away from her.
The head of the gynecology department at Ankara University, Professor Rusen Aytac comments that heteropaternal superfecundation is not common in humans. In order for this type of multiple pregnancy to occur, a woman would have had to release multiple ova in the course of a single cycle and have sexual intercourse with multiple partners within a small time span.
While heteropaternal superfecundation is quite rare among humans, it happens often in cats and dogs. Stray dogs have been known to whelp litters in which every puppy is from a different father. The uncommonness of this type of pregnancy among humans is due to their monogamous and heterosexual tendencies. However, it is definitely possible for a woman who has sexual relations with more than one man at short intervals during the same period of ovulation to become impregnated by two or more men.
The first recorded case of heteropaternal superfecundation was noted by John Archer in 1810. Archer, an American physician, wrote of a white woman who had sex with a white man and a black man within a short time span. The woman gave birth to one white twin and one mixed-race twin.
A more recent case occurred in Texas in June 2008. A woman gave birth to fraternal twins that had been fathered by different men. After DNA testing proved that the twins could not have come from the same father, the mother admitted having engaged in intercourse with two different men close to the date of conception.
The Encyclopedia Britannica notes that twins are defined as, "… two young who are simultaneously born from one mother." There is no mention that such twins must be of the same father. The advent of DNA testing has turned up more and more cases of twins with two different fathers. Of course, this is only possible in the case of fraternal twins, who come from more than one egg released during a single cycle.
There is a known case in which heteropaternal superfecundation occurred as a result of fertility treatments. A mix-up in the laboratory during an IVF procedure performed in Holland meant that equipment was used twice. This caused another man's sperm to mix in with that of the woman's husband and resulted in the births of Koen and Tuen Stuart.