Identical or Fraternal?

“Are they identical or fraternal?” is one of the most common questions parents of twins are asked. (“Did you use fertility drugs?,” “Are they boys or girls?,” and “How much did they weigh when they were born?” are others.)

diapers

If one twin is a boy and the other is a girl, the twins are always, always, always fraternal. They can’t be identical. As my mother says when anyone asks her if her grandtwins are identical, “Take a peek in their diapers and see.”

If there are two boy twins, or two girl twins, the situation is more complicated. Fraternal twins can look very similar, and identical twins can have some differences. When I was pregnant and didn’t yet know I was having a boy and a girl, I looked into the subject and found that DNA testing is the only accurate way to determine if same-sex twins are identical or fraternal. There are lots of casual ways for guessing, but it’s the DNA that tells you for sure.

Of course, if you have one red-haired blue-eyed boy twin and one brown-haired brown-eyed boy twin, you may want to save your money for their college education instead.

6 thoughts on “Identical or Fraternal?

  1. Kathryn

    Ha! After finding your MIL post through Sundry, I started reading your archives and came across this post. It reminds me of a (very, very stupid, as demonstrated on many occasions) neighbor of my parents.

    When I was about 10, she had twins, a boy and a girl. She brought them over for a visit, and sat around catching up with my mother. In discussing the twins’ birth, she said, in all seriousness, “Well, there are tests that can be done to see if they’re identical or fraternal, but I think we’ll wait.” My little 10-year old mouth just gaped at her, and my mom and I just tried not to look at each other, for fear of laughing.

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  2. shoeaddict

    My best friend’s sister has frat twin girls. They look nothing alike. They are seven years old now. Grace is a head taller than Emma, Grace has lighter hair, Emma has chubby cheeks. People ask Heather, the mother, all the time “How can you tell them apart?”

    Did you find out the sex of the twins while they were in utero?

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  3. Swistle

    Shoeaddict- Ha ha! We get that, too, although less now that Elizabeth has longer hair.

    Yes, we found out by ultrasound. I had a BUNCH of ultrasounds (every 6 weeks), and they couldn’t tell EITHER twin at several, and then they could see that Baby B was PROBABLY a boy but they couldn’t tell Baby A until the next ultrasound. Then finally they were certain on both.

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  4. Doing my best

    I’m glad you have archives; it’s like getting to read a favorite book again, and I still laugh just as hard as I did the first time I read most of your posts =) (…umm, because the other posts aren’t supposed to be funny…)!
    Oh my goodness! Elizabeth and Edward were just BABIES and now they’re full-fledged children! Can you believe that you survived those early days so well and with your mind and excellent ability to write still intact?!

    Reply

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