Two to Kiss, Two to Love: Identical or Fraternal

PC: Jackie Hall

When I was younger, as you've previously read, I wanted to have identical twin girls. So when I found out my dream had come true, and I was ACTUALLY having twins, of course, the next question on my mind was whether they were identical.

When the doctor first showed me the ultrasound, it was very clear the babies were in separate sacs, and looked like they would both form their own placentas. As far as I knew, this meant they would be fraternal. I turned to my doctor and said, "so they are fraternal twins then?" Her response, "you actually won't know for a while." WHAT? HOW?! There is a chance they could be identical!?! Do you know how awesome that would be?! YAY! All thoughts had by me within seconds of this new observation. So what did I do immediately when I got home? I researched all the different types of ways that my babies may possibly end up identical, duh. Did you know that there are something like 7 types of twins? Conjoined and mirror-image twins make it on that list. So, instead of making you do all the work, I'll at least sum up the difference between fraternal and identical twins, and how you know.

Fraternal Twins:

Fraternal twins, or dizygotic twins, are twins that come from two different eggs. Both eggs receive their own sperm. Essentially, fraternal twins are basically two ordinary siblings who happened to share a pregnancy. What twin mom wants to hear that? Just two ordinary siblings that I had to have at one time? And what if one is way taller, or one has red hair and the other black, etc, etc. I mean, hopefully my twins at least LOOK like twins. Like Mary-Kate and Ashley Olsen. Did you know they are fraternal? They are called fraternal look-alikes. At least make my babies fraternal look-alikes!

Identical Twins:

Identical twins, or monozygotic twins, come from one egg. The egg then splits. And tah-dah, identical twins.

As far as sacs and placentas go...

 Fraternal twins always have separate sacs and separate placentas. Always. Identical twins take on a few extra options. They can share the placenta and the sac, they can share the same placenta, but not share the sac, or they can have separate everything. Why? It's all based on the timing of the egg splitting. If the egg split by the third day after fertilization, these identical twins would have separate everything. If the split takes place within 4-8 days, the twins would share the placenta, but have different sacs. And if the split happens after 9 days, the twins would share everything.

How do you know?

So how do you know if they are fraternal or identical when they don't share a thing? First, wait until you find out gender. If your twins are boy/girl twins, they are OBVIOUSLY not identical. If they are the same gender, you're waiting until they are born mama.

And if you've been wishing for identical twins, don't be completely alarmed when your husband says, "they look nothing alike."

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*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!*