Are Your Twins Fraternal or Identical?

I’ve been asked this question several times throughout this pregnancy and I’ve always answered with this: fraternal. I have been so confident and sure when I say this because of the minimal research I had done. Like becoming pregnant with twins made me instantly knowledgeable about twin facts.

Well…I was wrong.

I’d like to preface this by saying sorry to anyone I told this to, because honestly, I thought I was right. However, I’ve done a little more digging and found the true answer.

And that is…I have no idea what they are. Let me explain.

So, our twin babies have their own placenta and their own amniotic sacs. To define this for baby newbies (like myself a few months ago), the placenta is what attaches to the uterine wall and is where the babies get their nutrients. The umbilical cord attaches to the placenta that attaches to the baby. The amniotic sacs are the little bubbles that a baby essentially floats in.

So to break it down, our twins aren’t really connected at all…they aren’t sharing a sac or a placenta. The only thing they’re sharing is my uterus. It’s like sharing a house, but they’ve got their own rooms.

Anyway, back to why I thought these kids were fraternal: having individual placentas and amniotic sacs are the only kind of fraternal twin. Fraternal twins occur when the woman dropped two eggs (hyperovulation) and then two different sperm fertilize those two eggs. Then they connect to the uterine wall and start growing like two, independent babies. That’s why they look different…they don’t share DNA like identical twins. It’s more work on the mama (tell me about it) but at least there isn’t a risk of one baby getting more than the other. Fraternal twins are also the only kind of twin that can be hereditary. And that’s because a woman can inherit hyperovulation (fascinating, I know).

I read about this, knew our babies were in their own amniotic sacs with their own placenta and automatically assumed they were fraternal. My theory was that I had dropped two eggs after coming off the pill. Like my body was like, “Hey, we haven’t ovulated in a while. How does this work again? Oops, we dropped two.”

Once at a doctor’s appointment, I even made the comment about them being fraternal. The nurse laughed and said, “Well maybe, we’ll see.” I was like, “Uhm, what does she mean by maybe? Google said…”

Well, who’s laughing now.

This brings me to identical twins. There are THREE kinds of identical twins. Identical twins happen when one sperm fertilizes one egg and then splits. So the kids share the same DNA makeup. The first type of identical twin occurs when the split takes place while imbedding in the uterus. This causes the twins to share a placenta, but still be in separate amniotic sacs. The second kind is when the embryo implants and then splits later on. The babies can share a placenta and a sac. BUT, if that one sperm and one egg embryo splits before implanting in the uterus (like way early on), the babies can have two different placentas and two different sacs….like our twins. Which would make sense, because having identical twins is not hereditary. They’re total flukes. So, that would answer our question of being blessed with twins when this doesn’t run on either side of the family.

This means the only way to know if they are fraternal or identical while they’re still in the womb is if it is a boy and girl at the gender reveal…because they can’t be identical twins if they don’t have identical genitals (I mean, hello).

However, if they are same sex, we will have to wait to SEE them to know if they’ll be identical or fraternal. Fraternal seemed easy, like we’d have eye color or hair type to tell them apart. If they’re identical, am I going need to label their diapers????

Anyway, to answer your question, I have absolutely no clue if we are having identical or fraternal twins.

And apologies for confidently telling everyone that we were having fraternal twins. I was super wrong.

(I’ve included pictures off the internet below, in case my rambling made zero sense to you…or if you’re a visual learner.)

Here are the resources that educated me, in case you want to read up:

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