Two to Kiss, Two to Love: Do Twins Run on HIS Side?

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Twins are a wonderful thing. They are the cutest gift you’ll ever receive as a twin mama. And what comes with this amazing gift? Tons of questions from random strangers who also think you have been given this spectacular gift!

My husband has a brother who has a set of fraternal twins. My twins are also fraternal. Both sets of twins were conceived without the aid of fertility drugs. It ALWAYS amazes me when I think of my mother-in-law and her children. TWO of her three children have twins. Again, two-thirds of her kids have twins! That’s pretty incredible. How many people do you know who can say that?

Once someone knows that my husband’s brother also has twins, I inevitably get asked if twins run in HIS family. What I’m really being told is, “Oh, you had twins because of your husband’s genetics.” Every time I’m asked this question, or told I have twins because of HIS family, I’m left in a stupor. When I’m asked”Do twins run on your side of the family or your husband’s?” outside of knowing that my husband’s brother has twins, I’m even MORE astonished. So, let’s get some educating out of the way, shall we?

Women drop eggs, not men, right? Women produce the egg that might split and create identical twins. That being said, a man’s genetics have no effect on this whatsoever. It is truly incredible that my mother-in-law has two sets of twin grand-babies since both sets have to do with her daughter-in-laws dropping eggs, and NOT her own sons. Did those brothers know how to pick fertile women or what? Ha. OR, maybe they have magic sperm that are calling the eggs to come down two at a time? Possible? Probably not.

I was always under the impression that fraternal twins were based off of the women’s genetics, but my doctor told me that they are beginning to think that may not be true; that there is a twinning rate and it can happen to any woman. So here’s how genetics play a role in the making of twins; still, ONLY with the mom’s genetics (well, except in the case of magic sperm 😉 ).

When two egg cells are each fertilized by a different sperm in the same menstrual cycle, fraternal twins are the result. Genetic Home Reference states that fraternal twins are twice as common as identical twins, and “are much more likely to run in families.” If your mother or sister had fraternal twins, you are twice as likely to have fraternal twins. However, fraternal twins are “thought to be the result of hyperovulation, which is the release of more than one egg in a single menstrual cycle. To explain how [fraternal twins] can run in families, researchers have looked for genetic factors that increase the chance of hyperovulation. However, studies examining the contributions of specific genes have had mixed and conflicting results. Few specific genes in humans have been definitively linked with hyperovulation or an increased probability of [fraternal twins].”

So basically, fraternal twins show up more often in families who already have them, but they aren’t actually absolutely sure it’s only because of a women’s genetics. Neither my sister-in-law, nor myself, have twins in our close families; maybe way, way, way down the line somewhere that we just don’t know about yet. So who knows why we had them?! Are you starting to think that the “magic sperm” thing might be true? (No, no, a man’s genetics still have nothing to do with the eggs.)

Now, identical twins are absolutely all mom here–no magic sperm stories. It is thought that anyone can have identical twins because your egg is splitting in two. “Identical twins occur when a single egg cell is fertilized by a single sperm cell. The resulting zygote splits into two very early in development, leading to the formation of two separate embryos,” GHR tells us. “However, a few families with a larger-than-expected number of [identical twins] have been reported, which indicates that genetics may play a role. It is possible that genes involved in sticking cells together (cell adhesion) may contribute to [identical twins], although this hypothesis has not been confirmed.”

So fraternal, or identical, your twins are all you mama. Now you can confidently tell those on-lookers that dad’s genetics have nothing to do with getting your twins.

And to you mamas who are wishing for twins, good news for you! You have the same possibility of having identical twins as anybody else, and who knows, fraternal twins might even been down your alley…remember, I don’t know anyone else in my family who has them.

Mama Jackie


*The “Two to Kiss, Two to Love” series is a helpful series for all you twin mamas out there! If you have a twin related question, comment below, and I’ll answer it for you!*

Featured Image PC:@alicianicolethomas

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