/span > In this case, both twins would be born with two biological fathers. The first documented case of twins born with different fathers was in 1697. The doctors at the time believed that they were twins because they were born on the same day with similar marks on their faces. They also had similar colors around their eyes and lips. One boy lived only three days while the other survived for five months. Scientists now know that these babies were not true twins - they were fraternal triplets who shared some organs/tissues/cells with each other. True twins are individuals whose eggs have been fertilized by two different sperm cells. They usually appear about two weeks after conception and can be distinguished by their differences in size and shape. There are several cases in history where children have been found to have had multiple fathers. For example, an English court in 1669 declared one child to be the son of one man and the father of another because they resembled each other so much. These boys were born nine months apart and lived together with their mother. When the boys grew up, it was discovered that they belonged to two different men who had impregnated the same woman.