However, some scientists now believe that familial monozygotic MZ twinnning occurs more often than had previously been believed and may have genetic factors. So, your family history may increase your chances of having identical twins, too. However, the chance of having identical twins run in your family is rare. Only around 3 or 4 in every 1, births are identical twins. However, any female children of twins could inherit a combination of genes that makes them more likely to release multiple eggs during ovulation thanks to the DNA passed from their dad.
This would make them more likely to have twins and give the appearance of the twins skipping a generation. Why are the chances of twins so much higher with fertility treatments? Many fertility drugs work by increasing the number of eggs the ovaries produce, thus increasing the chance of multiple eggs being released and fertilized to produce fraternal twins. Additionally, as part of in vitro fertilization IVF , a woman may be implanted with multiple embryos to increase the likelihood of one implanting.
While this raises the likelihood of becoming pregnant, it also increases the chances of having twins. Having twins may seem about as likely as winning the lottery. After all, only an estimated 3 percent of pregnancies per year in the United States are multiples. So there's a 3. But a few factors — not just heredity — in moms can up the odds of having twins.
These include if a mom is:. What to Expect follows strict reporting guidelines and uses only credible sources, such as peer-reviewed studies, academic research institutions and highly respected health organizations.
Learn how we keep our content accurate and up-to-date by reading our medical review and editorial policy. The educational health content on What To Expect is reviewed by our medical review board and team of experts to be up-to-date and in line with the latest evidence-based medical information and accepted health guidelines, including the medically reviewed What to Expect books by Heidi Murkoff.
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Do Twins Really Run in Families? Do twins run in families? Continue Reading Below. In addition, we don't know if the gene requires something in the environment to activate it. Geneticists used to think that identical twins don't run in families, that the splitting of the fertilized egg happens randomly.
While research has shown that most cases of MZ twinning are not genetic, there are families with larger-than-normal numbers of identical twins, which means there may be something genetic going on. One explanation is that MZ twinning might happen because of a mutation in a gene or genes that control how the cells of early embryos stick together. The embryo with this gene may not stick together as well, and this could cause it to split before it's implanted.
The gene for hyperovulation can come from either side of the family, but the woman would need to have the gene in order for the couple to have twins based on genetics. In other words, twins on the father's side of the family will have no influence on your chances of having twins. It's possible, though, that if Dad inherited the gene for hyperovulation, he could pass that gene onto daughters, increasing their chances of twinning — and yours of having twin grandchildren.
Think you might be having twins? A first trimester ultrasound will confirm that you are, but there are some early signs of a twin pregnancy that might make you wonder. Read our article on signs you're having twins or multiples to find out more. BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world. When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals.
We believe you should always know the source of the information you're seeing. Learn more about our editorial and medical review policies. Hoekstra C et al. Dizygotic twinning. Human Reproduction Update 14 1 The same is not true for fraternal twins.
So, having identical twins is not due to genetics. On the other hand, fraternal twins can run in families. In fact, a woman that has a sibling that is a fraternal twin is 2. Fraternal twins happen when two eggs are simultaneously fertilised instead of just one. There appears to be a genetic link that predisposes some women to hyperovulation, which means releasing more than one egg during ovulation, or each menstrual cycle. Heredity on the father's side does not increase a couple's odds of having multiples.
This is true even if his family is full of multiples.
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