Fraternal Twin Boys: Five Things Parents Need to Know

For years, researchers have studied the six twin subgroupsidentical twin boys (MZm), identical twin girls (MZf), fraternal twin girls (DZSSf), fraternal twin boys (DZSSm), and of course, opposite-sex twins, DZOSm and DZOSf—and have come up with a list of general characteristics for each. The following list of five things you should know about your fraternal twin boys is here to act as a guide, and perhaps offer you just a little peace of mind. But remember, these are just generalities based on research from a control group of twins. Your twins may be the exception to the rule and defy them all. And while it’s never a good idea to stereotype any group, it’s helpful to understand the subtle variations that from time to time crop up among all the different types of twins. 

  • As toddlers, fraternal twin boys will wear you down to the point of exhaustion. 

two twin boys smiling for cameraUnlike twin girls who tend to sit and play together for lengthy periods of time, fraternal twin boys are often more physically active, preferring to examine their worlds through action. I know this first hand as I’ve often written about those chaotic toddler years. I can remember heading to the store with my toddler boys and from the moment we ventured inside, they’d take off running in opposite directions. Not because they wanted to be naughty and deliberately break things. No, they were good kids. But they were curious little guys and wanted to see and touch everything.

So how is this knowledge helpful?

Just knowing that the craziness is normal can be reassuring (to a point, of course). From the moment your toddler twin boys wake in the morning to the moment their heads hit the pillow at night, they will be on the go. That’s just the way it is. In order for you to survive, however, you’ll need to prepare. That means keeping those twins busy! From weekly play dates and park outings to high-quality preschool that focuses on active play time, if your boys are engaged, they’ll be happy. And when they’re happy, so are you! Remember, when you have toddler twin boys, there’s no such thing as “over scheduling.”

  • Research shows that fraternal twin boys tend to be the most aggressive of all twin subgroups.

That explains the constant hitting, biting, pushing and arguing, doesn’t it? But on the plus side, fraternal twin boys also exhibit high leadership skills and are more assertive in articulating or expressing what they think are their rights. (“Hey, that’s my toy!”) It may drive you crazy now when they’re toddlers as it’s not easy arbitrating their “toy wars,” but it will serve them well once they hit the school years.

  • They may not be the best of friends…for now.

Although many fraternal twins are close, calling each other “best friend,” many fraternal twin boys prefer the company of someone other than their cotwin, especially when they hit the school years and begin to bond with their classmates. This may never be an issue in your house if both boys are on the same page, each having an outside best friend. Or, it can be the source of pain and conflict if one twin wants to continually find outside play dates at the exclusion of his cotwin.

So how is this knowledge helpful?

It’s all normal behavior. Try to remember that they are merely two siblings born on the same day and may have two very different temperaments, personalities and passions. Don’t try to shame or guilt the independent twin into hanging out with his brother when he may not want to (“But he’s your twin!“) as it will surely backfire. Instead, respect his right to have outside friendships and then encourage the dependent twin to do the same. When you allow each to be an individual, something magical happens—they are then free to be friends with each other again, no strings attached.

  • Fraternal twin boys are usually more competitive and rivalrous than other twin subgroups.

From the time they were little, my fraternal twin boys have always tried to outdo each other. It used to be a competition to see who was taller; now it centers mostly on who gets better grades in school. (“Ha-ha! I got two point higher on my math test!” or “I scored 100 points higher on my SATs!”) It never seems to matter if they don’t quite measure up to their friends; they just want to eclipse their cotwin.

So how is this knowledge helpful?

Ignore it. Don’t play into it. A little bit of twin rivalry is actually healthy as it teaches kids how to negotiate and handle conflicts. Plus, I think they truly enjoy the verbal sparring with one another as it gives each the opportunity to fine-tune his tongue. (I wonder if a large number of lawyers are fraternal male twins!)

But if you sense that your twins’ competition is getting out of control, take a look at your own behavior. Be very careful not to openly compare your twins even with a seemingly innocent positive comparison (“Wow! You did great on your test! You scored even higher than your brother!”) You may want to consider placing them in separate classrooms at school, too, or offer them the chance to play on different sports teams. Finally, make an effort to spend alone time with each twin individually.

  • Fraternal twin boys may be very physically different.

Different genes, different people. It’s bound to happen. One twin may be blonde, the other a red-head. One boy may need glasses, the other may have 20/20 vision. It’s all par for the course and for the most part readily accepted by the twins themselves.

So how is this knowledge helpful?

But then there’s the issue of height. To many fraternal twin boys, being shorter than your classmates is bad enough but to have your cotwin tower over you by several inches hurts all the more. If you feel that the physical differences between your twins is a sensitive issue, loving reassurance can go a long way. For instance, did you know that thin siblings usually reach puberty at a later age than even slightly overweight siblings? Furthermore, boys are lucky in that they can continue to grow well into their late teens and early twenties (compared to girls who usually stop growing shortly after their first periods.)

And when friends and family publicly point out your twins differences (“Isn’t it funny how Bobby is a full head taller than Jeffrey?”), step in discreetly asking them to table the conversation.


17 thoughts on “Fraternal Twin Boys: Five Things Parents Need to Know

  1. Vanessa Armstrong

    Very insightful, not because my twins are boys, but because I have a son 3 years older than my twin girls (they are 18 months). I look forward to the possibility of this article on fraternal girls!

    1. Christina Baglivi Tinglof Post author

      It’s coming next and it’s sooooo interesting! (In a good way, I promise.) Thanks for commenting.

      1. dakotapam

        I’m looking forward to that too. My fraternal twin girls are 3.5 and have a very unique relationship compared to my singleton boys!

  2. Jen

    I’m feeling really vindicated by #1. I have friends with identical and fraternal twin girls, and no one seems to be driven as insane or as tired as I am by two 18 month olds. I’m glad to know I have good company. ;-)

    1. Christina Baglivi Tinglof Post author

      Absolutely! The toddler years were hard! But there is light at the end of the tunnel–my twin sons have been playing cards (peacefully!) with friends for the last three hours! Bliss.

  3. ARolle

    This is very helpful I have 20 month old fraternal twin boys and they are busy it just helps me to know what to expect and clarify that things I was concerned about I don’t need to be … very insightful

  4. Charlotte Annett

    Always interested in information.I have fraternal twin boys and another
    two more boys one older ,one younger.(4 boys under 4 years old)
    I feel like I have triplets and a newborn.
    Interested in information about there development ,behavior etc.

  5. Ana

    Amazing! Except for the height issue (so far, because they’re only 2) you just described my b/b fraternal twins! It’s a relief to read all this, thank you!

  6. Sara

    What a great article. My fraternal twin boys are 9 months today and it is always helpful to see what I will be up against in the years to come.

  7. Brandi

    I have fraternal twin boys who are now 12. The search phrase I used to find your site was “twin mom of teen boys needs help”. Almost every point made resonates with me.

    The size difference, the personality differences, the arguing – in 6th grade and just being in middle school is hard enough, puberty.. all are unchartered waters that I feel like we are about to drown in and it’s only week 3 of school.

    We have 4 – our oldest girl is 19, sophomore in college, the boys are 12 and our youngest girl is 8. One of our twins has required so much attention since he was 4 that he has dominated the home and usually not in positive ways. I keep telling him (and reminding myself), you are going to make a great leader one day. With all of the attention going to one for so long, the other one has gotten lost in the shuffle. As a mom, I cannot comprehend a bigger fail in my role as mom than “losing” one of my kids in the shuffle.

    He is the quiet one but a lot goes on on the inside.. we are at a critical point in his life and I am out of tools in my tool belt. I’m a bit exhausted and just physically worn out. He is four inches shorter and if people only knew pointing that out is offensive, perhaps they would refrain.

    This is so specific to twins and I have no friends with twins so there truly is a lack of understanding and a group to glean from.

    I am looking for help, I am an avid reader and a Christian. Any input would be most appreciated!

    1. Christina Baglivi Tinglof Post author

      So much to say…..but mostly I can totally understand when you say you don’t want to lose one of your kids in the shuffle. As a mother too, I am always wondering if I can do more, or if what I’m doing is right or helpful. Parenting is a huge crap shoot! I honestly don’t know what the answer is as I’m not a doctor but I can offer you this – I, too, had a “willful” child (I’m guessing that’s how you would describe your son when you say he dominates the house and not in a positive way). There were times that I couldn’t even be around him because he was just so nasty. Yet now he’s a sophomore in college, and he has matured. He’s PLEASANT and INSIGHTFUL and understands what a pain in the ass he was as a child. He’s says that being on his own, and out from under my thumb (I guess he didn’t like my rules) has helped him. Now waiting for your 12-year-old to turn 18 and head off to college isn’t much comfort but there are plenty of books out there to help you navigate this tricky time. Plus, there are several psychologists who specialize in twin issues and relationships. They even offer phone consultations. Look up/Google Dr. Joan Friedman, author of several books on the twin bond, and Dr. Eileen Pearlman, a psychotherapist in Santa Moncia, CA. Both women are twins, too!

  8. Rianet

    My fraternal twin boys are now 13 and I found this article spot on…. thank you. People without twins have no idea of the challenges we as twin parents face… and then we just stay on our knees, praying that we have done the best for them… thank you for the article.

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