Are Twins Pregnancies Hereditary?

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Posted by vera | Posted in Twins or Multiple Birth Pregnancy | Posted on 19-03-2013

DNA renderingAn often asked question when you tell people you are pregnant with twins is “do twins run in your family?” There is a lot of talk about twins “skipping” a generation, and other misconceptions also exist.

As it turns out, dizygotic (or “fraternal”) twins are hereditary, but only on the mother’s side. A genetic trait that tends to cause “hyper-ovulation” (the releasing of multiple eggs per cycle) can be passed from mother to child. Of course, as babycenter.com points out, it’s important to remember that “a man who carries the gene doesn’t have a greater chance of having twins himself because his genes don’t affect his partner’s ovulation.” Hence, it may seem to “skip a generation” when a father passes on his mother’s gene to his daughter. (i.e. “My grandmother had twins, so does that mean I could, too?”)

Some cultural groups seem to have a higher incidence of this genetic trait. For example, dizygotic twinning is quite rare in Asian women, about half the rate of Caucasian women. Women of African origin, meanwhile, have four times the chance of Asian women of conceiving twins! That being said, some twins seem to occur spontaneously, too.

Monozygotic (or “identical”) twins, on the other hand, are NOT hereditary, and occur randomly regardless of age or race.

Artificial reproductive technology (ART) has increased the incidence of both types of twins, though mainly dizygotic twins are more common now, due to an increase in fertility treatments which stimulate the ovaries.

Many of our prenatal class clients past and present are expecting or already parenting both mono- and dizygotic twins, triplets or more due to ART.

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