Poland: A pair of twins born in Poland have different fathers, Polish media reported Monday -- in apparently only the seventh such case in the world.

The twins' mother became pregnant while she was having relations with her husband and also having an affair, reported broadcaster TVN 24.

The woman, whose name was not given, filed for a divorce after giving birth to the twins, one male and one female.

The woman later conducted tests to prove her husband was not the father of either child.

The tests showed, however, that the husband was the father of the baby boy, while the other man was the baby girl's father.

Such rare cases are possible when a woman produces two eggs and has sex with another partner while she's ovulating, local media reported.

Tags: different fathers, Poland, twins