It might sound crazy to some people (maybe even taboo to others), but a pair of identical twins marrying identical twins is called a quaternary marriage. Although rare, they do happen. Unsurprisingly, these couples may even go on to have identical twins of their own.

Where do twins come from Mom or Dad?

For a given pregnancy, the odds of conceiving fraternal twins are only determined by the mothers genetics, not the fathers. Fraternal twins happen when two eggs are simultaneously fertilised instead of just one.

What is full term for twins?

While 40 weeks is the full gestation period of the average pregnancy, most twin pregnancies are delivered at approximately 36 weeks (range 32-38 weeks depending on the type of twin pregnancy).