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If I Have Twins in My Family, Will I Have Twins?

Understanding the connection between twinning and family history.


Updated May 30, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Read Part One of this article...

If I Have Twins in My Family, Will I Have Twins?

I don't have a crystal ball to know whether someone will have twins or not. If I did, I'd use it to play lottery numbers! If you have a family history of twins, and wonder whether you will have twins, consider these factors:
  • What kind of twins are in the family?
    Remember, monozygotic (identical) twins don't run in families; they're random. You may not know if your great-granduncles were identical or not; often there is no way to know for sure without DNA testing. However, twins that share a close physical resemblance are more likely to be monozyotic. Boy/girl twins are always fraternal (dizygotic).

  • Are the twins a result of assisted reproduction?
    In the last ten years, a large number of twin and multiple births can be attributed to fertility treatments: fertility drugs and invitro procedures. If your cousin had twins after taking Clomid, it has absolutely no impact on your chances of having twins.

  • Whose side of the family had twins?
    Let me talk to the women for a moment, since they are the ones who usually ask me if they'll have twins. If the twins are present on your husband's/partner's side, it won't influence your chances of having twins. Remember, the gene for hyperovulation is only a factor for the mother. If your mother -- or your grandmother or aunt -- was or had fraternal twins, then you might have the gene. But your husband's family history has absoultely no bearing on your own children, except maybe for the future possibility that you might have twin grandchildren!

  • What other factors are at play?
    Remember, a family history of twins is only one of many factors that influence multiple birth. Maternal age, race, weight, diet and reproductive history all contribute to twinning and may have a stronger influence than family history. Consult my resources on How to Have Twins to understand these other factors.
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