Re: Twins born - fathers different.
Superfecundity !
Its when 2 ova are released in the same cycle and both get fertilized by sperms from two separate acts of intercourse ....
**Superfecundation most commonly happens within hours or days of the first instance of fertilization with ova released during the same cycle. **
**There is a small time window when eggs are able to be fertilized. Sperm cells can live inside a woman’s body for 4–5 days. Once ovulation occurs, the egg remains viable for 12–48 hours before it begins to disintegrate. **
Thus, the fertile period can span 5–7 days. Ovulation is usually suspended during pregnancy to prevent further ova becoming fertilized and to help increase the chances of a full term pregnancy. However, if an ovum is released after the female was already impregnated when previously ovulating, there is a chance of a second pregnancy—albeit at a different stage of development. This is known as superfetation.
It is very rare in humans but occurs more commonly in cats and dogs.