Twinning in itself is a phenomenon that captures the interests of millions of people. That's the reason there is a Twins Site here at BellaOnline! Mix in the reality that there are twins who exist that have been fathered by different men, and the imaginations of outsiders wondering how such an event could happen increases that curiosity.


Bi-paternal twins are always fraternal. Fraternal twins are the result of two eggs being fertilized by two different sperm, most commonly produced by one man. Identical twins are the result of one egg splitting and therefore cannot have different fathers. The conceptual process of bi-paternal twinning goes a step further in that the two eggs are fertilized by two different sperm belonging to two different men.

The most common cases of bi-paternal twinning result from the mother having intercourse with two different men, and having one egg fertilized by each man. Bi-paternal pregnancies are often the result of prostitution, so statistics outlining the numbers of cases of bi-paternal twins aren’t reliable due to the mothers being less than forthcoming about the babies’ conception.

Less common instances in which bi-paternal twinning occurs when fertility treatments are used. Although fertility centers are taking extraordinary precautions to make sure this does not occur, some have admitted to such errors. There are cases where a mother's egg has been mistakenly joined together with her husband's sperm and an unidentified donor's sperm, resulting in two eggs fertilized during one pregnancy. The resulting births could range from the children being different races, for example, one black child and one white child; or the children could be born of the same race but with strikingly different physical characteristics, which were adopted from their respective father’s genes.

A pregnancy that is the result of bi-paternal twinning poses no additional risks for the mother or the babies outside of the normal risks a multiple pregnancy brings.