Do Twins Run in Families?

Joe Rawlinson by Joe Rawlinson - August 9, 2021

One of the most frequent questions my wife and I receive when people find out we have twins is, “Do twins run in your family?”

Idenitcal Boys

I always want to say, “Yes, they run all over the place now.”

Keep in mind that there are two types of twins: identical and fraternal.

Identical Twins

Identical twins are a random occurrence and have no connection to your family history. If you have identical twins, like we did, you can say you won the twin lottery. The odds of having identical twins are about 1 in 285, regardless of age, race, or family history.

Since identical twins are random, your twins are no more likely than you were to have twins of their own.

Fraternal Twins

Fraternal twins happen when the mother releases two eggs that are both fertilized.

There is a genetic disposition in some mothers to hyper-ovulate. This condition can be hereditary.

4 Critical Mistakes Expectant Twin Parents Make

Dads, your family history has no impact on whether you will have twins or not. This is true even if you are a fraternal twin or you have a parent that is a fraternal twin. No matter what you do, you can’t ovulate and thus any family history of twins is irrelevant.

The odds of fraternal twins increases when the mother’s family has a history of hyper-ovulation and fraternal twins.

Increasing Your Odds

The older a mother, the more likely she is to release more than one egg, even if she has no family history of twins. Certain fertility drugs also increase your odds of fraternal twins.

(RELATED: Check out the Dad's Guide to Twins Youtube channel for additional helpful twin tips and tricks videos.)

The bottom line, however, is that the mother’s family history is the biggest factor in you having fraternal twins.

Do twins run in families? Yes, they run all over the place.

Tired of answering this question all the time? Just wear this t-shirt and it can answer for you:

twins-run-mockup_top

Picture by Ankur P

Twin Gender Predictor Calculator

Further Reading

Dad's Guide to Raising Twins book
Don't forget to pick up a copy of the definitive guide to raising twins. "Dad's Guide to Raising Twins" was written for fathers of twins to help guide you through the first several years with twins. Click here to learn more about the book and get your copy.

6 thoughts on “Do Twins Run in Families?”

  1. My husband has quite a few twins in his family, especially identical twins. None that I know of from mine. We have identical twins so it makes me wonder if it can ‘run in the family’. I know of quite a few identical twins that end up having identical twins.

    Reply
  2. @Gianna – While it may appear to be hereditary, it probably isn’t. There is some good info on about.com on this: “There’s no hereditary trait that influences a predisposition to having identical twins. Identical twins do not run in families. Although there are families with a high incidence of identical twins, it is due to chance, coincidence or plain good luck.”

    Reply
  3. I’m 8 weeks pregnant with fraternal twins and in my early twenties. I don’t have any family history of twins at all although my partners mother is one twin of a set of fraternals. I find it extremely unusual that figures show fraternals run on the women’s side although the fact is on my side there is none but my partners side there is… Is this just a freaky incident?

    Reply
  4. @Shona – Congratulations on expecting twins! Fraternal twins can be born in families even without a family history of twins on the mother’s side. This is likely the case in your situation. To get fraternal twins, you would have released two eggs that were fertilized. That could be due to natural reasons or if you were using any type of fertility treatments.

    Reply

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