What if I am using clomiphene (Clomid®) to help with ovulation?
Yes; family history is a strong factor. If you are a twin yourself (non-identical), then you have a higher than average chance of having twins yourself. The same applies if you have first degree relatives who are twins (non-identical).
The chances of having a twin pregnancy also increase with age and the number of pregnancies. This means, the older you get and the more pregnancies you have, the higher the chances of getting a twin pregnancy.
The rate of this kind of twins is constant throughout the world and is not influenced by age, race, family history or the number of pregnancies.
If you are an identical twin yourself, your chances of having a twin pregnancy is the same as the average.
Tressa Montalvo gave birth to quadruplets who were actually two sets of identical twins on Valentine’s Day in 2013. The odds of this happening is estimated to be 1 in 70 million
What if the father is a twin?
If he is an identical twin, then there is no increase in the chance of twin pregnancy. If he is a non-identical twin, then there is some increase in the chance of a twin pregnancy, though not as high as when the family history of twins is maternal.
With identical twins (doctors call them "monozygotic"), it is the result of the division of an already fertilized egg.
With non-identical- twins (also called "dizygotic" or "fraternal"), it is because of fertilization of two separate eggs that happened to be released at the same time. Most twins are non-identical.
Virtually all higher order multiples (triplets and so on) are non-identical.