Boy-Girl Twins: 5 Things Parents Need to Know

Out of all the twin types, boy-girl or opposite-sex twins have always been the most fascinating to me. After all, they get all the benefits of the twin bond without all the pressure. They have a play mate and confidant but by nature of their opposite sex, travel in different social circles and usually have vastly different interests and hobbies. It makes for a great life-long friend minus the comparisons and competition that same-sex twins sometimes come up against.

But like all relationships, boy-girl twins can have their ups and downs, too. Heredity and nature dictate that the two will develop at different rates from the moment of conception with the female twin almost always taking the lead. (According to scientists, although boy-girl twins may appear to be the same size at birth, inside the girl is developing at a much faster rate.) This can present a few challenges especially during the first few years of school. So if you have young boy-girl twins in the house, here are a few points you should keep in mind. But remember, these are just generalities based on research. Your twins may be the exception to the rule and defy them all.

  • Male and female twins reach fine and gross motor skills at different times.

As a rule of thumb, females grasp fine motor skills—those talents that involve small muscle coordination and dexterity—sooner than males. (Think shoe tying, buttoning clothes, even holding a crayon.) Males, on the other hand, usually master large muscle control and therefore reach gross motor skills earlier than females. (Think walking, jumping, ball throwing.) Therefore, no need to worry if your son walks months sooner than his cotwin sister or that your toddler daughter has mastered the art of dressing herself while her brother struggles greatly at first.

  • boy-girl twins huggingLittle girls usually surpass their cotwin brothers academically.

Research indicates that on average, boys lag academically behind girls during the early primary school years. It doesn’t mean that little girls are more intelligent, however. It just suggests that girls “get it” a bit sooner than boys but boys usually catch up and sometimes surpass their sisters by middle school. So what does that mean to your opposite-sex twins? If your female twin outperforms her male cotwin scholastically it could have a negative impact on his self-esteem, especially if they share a classroom where the differences may be more readily noticed by others and perhaps commented on. If you find yourself in this situation, you may want to separate your twins allowing each to develop at his and her own pace in his or her own preferred learning style.

  • Girl twins sometimes socially dominate their cotwin brothers.


Walk in any kindergarten classroom and you’ll see it—a little girl who is definitely in charge of the room! She is a social butterfly—the Queen Bee—who seems to be in everybody’s business (whether they want her there or not) directing her classmates in all matters. Since girls mature sooner than boys and are more verbal at an earlier age, it’s a natural fit. Personally, I like a girl with spunk but if she has a cotwin brother who continues to take a back seat to her bossiness and even seems to enjoy it (for instance, if he constantly allows her to do everything for him from tying his shoes to pouring him a glass of milk), it could have negative implications on both further down the road. The female twin may get a distorted view of all boys, thinking they are inept and helpless, while the male twin may begin to assume all girls are intrusive and headstrong.

Try to keep your boy-girl twins’ relationship balanced by stepping in before the passive twin becomes dependent and the dominant twin becomes the constant care giver. It helps if you encourage your twins to be independent and to do for themselves.

  • Boy-girl twins become aware of their sexual differences sooner than same-sex twins or singletons.

Due to their close physical proximity (shared bedroom, shared bath time and so forth), opposite-sex twins realize they have different “parts” sooner than either same-sex twins or single-born children with older siblings. This can cause some interesting (and dare I say) funny questions about their dissimilar bodies, all a bit sooner than perhaps you’re personally comfortable discussing. As kids are a curious bunch, there’s really no way around this so be prepared with some simple and short answers.

  • Puberty for boy-girl twins can be years apart.

The onset of puberty for girls hits somewhere between ages 10 to 14. The average for boys, on the other hand, happens between ages 12 to 16. Adolescence, therefore, can be years apart for some twins. And their physical and emotional experiences during this time couldn’t be more different either! So imagine, for example, if your female twin hits puberty full-force at age 12 while her brother still has a high-pitched voice and not a pubic hair to be found! Twins who were once a close-knit pair may experience a temporary “break-up” in the early teen years as she matures physically, emotionally, and socially much faster leaving her brother left wondering what in the heck happened to his sister.

Yet this, too, will pass. By the second half of high school, most boys have caught up or even surpassed their cotwin sisters in height. Socially they’re on a more even playing field as well. So much so that many boy-girl twins have a much greater understanding and sympathy of the opposite sex than their single-born friends. Once again, the relationship between boy-girl twins is able to blossom, grow, and mature marking the way for a socially happy adulthood.


24 thoughts on “Boy-Girl Twins: 5 Things Parents Need to Know

  1. twinzees

    I am going through this now. My daughter seems a few months more ahead in development than my son. Yet, we hurry him along, leaving him very frustrated. We always have to remind ourselves to step back and let him tell us when he is ready and that he will set his own pace.

  2. Twingirl22

    I’m the girl of a boy-girl set of twins, and we’re 14. We fight ALL THE TIME. I’m a much more optimistic and cheery person, while ever since my brother began to hit adolescence he’s been sullen and down-trodden, with a butter and mean attitude. He refuses to even let me acknowledge him at school! It seems like he’s always ready to pick a fight. Granted, I do start some of the fights, but some casual compliments I try to make are often hurled back at me or just given a “Shut up”. We’ve always fought with each other to some extent, but he used to be so sweet when he was little! So, on the contrary to your article, I’m wondering “What the heck happened to my brother?!?!”.

    1. Voss

      Hello, I’m not sure if anyone responded to your post or not, anyway I am male I have a twin sister, we are 20 now and have always been close, but in early high school I did the same thing as your brother this for me at least is was partly to do with space, and I felt like my sister embarrassed me, and made me look bad. It didn’t take long for our bond to grow stronger through it though. Ever since we were young we had to share everything: a room, a bed(for a few years), most birthday and Christmas gifts, since you are developing faster, (more mature as well as other things) your brother feels like he is being treated unfairly. I know with my sister she always had better marks then me and our parents would ask me why I couldn’t do as well as her.

      Long story short, your brother will come back to you you just have to give him time and space and you will have a friend like none other, it is a extremely unique bond few of us have. We have been living together for about a year now in a apartment we are both going to the same university.

    2. Twin girl has a twin brother

      Same here, we go to different schools but when we went to the same school he was like that and even when I talk to him with his friends he was so mean!
      Oh well, ignore it, he will be nice at home!

  3. Sonya

    Very interesting read. My kids are now 13 and there has definitely been a difference once puberty hit. It doesn’t help that my girl is in the 90 percentile for height and has towered over her brother for a few years, but he has started catching up. As for motor skills I didn’t personally see this, and have to laugh because my boy can’t throw a basketball to save his life whereas his sister is pretty good. She is definitely the more social of the two and she resents that he enjoys hanging out when her friends come over, constantly stating that he needs to find his own friends. I can see that she gets along well with guys because she can talk their language courtesy of having a twin brother, and vice versa for my boy. They were in kindie together and I separated after that which was the right choice for my two. She is advanced academically whilst he has struggled and when they were together he wouldn’t even try. Probably the best thing for him was when she got answers on her homework wrong and he was able to see that she wasn’t perfect. It has been an interesting journey so far. I am now heeding wise words from a mother further along in her journey, I will be actively discouraging either to date the others’ friends.

  4. Ari

    Oh WOW, this fits my twin brother and I TO THE T. Especially the bit about the tying shoes earlier but him learning to walk earlier, the academics and the girl being more extroverted than the boy. I just assumed it was because I was the older twin that it was like that…
    And, yeah, the sexual differences too! Our parents always tease us because I always said that “I wish I had a ‘nose’ to pee with like Alex (brother)does” and we both used to ask the doctor whether I could get myself a ‘nose’ whenever we had a check-up ^^

  5. Kimla S.

    I am Mom to 4 yr old boy-girl twins…Gabriel and Abigail. Being a Twin Mom is a double blessing, it requires double effort AND double energy…but I wouldn’t change a thing. Thanks for the article, it appears you wrote this awhile ago but it is still useful…please keep writing. :)

    1. Christina Baglivi Tinglof Post author

      Thanks for the positive comments! It does help keep me going!

  6. Tolina Butler

    I have boy/girl twins who will turn one on the 27th of this month and I have noticed already that they develop at their own pace. My son is the oldest of the two by 2 minutes. They have a great bond and console and entertain one another. I love it. My son is already walking/crawling and has two bottom teeth while my daughter is just now really learning to crawl and she has 4 teeth on the top and two on the bottom. I would say that they alternate on the talking. Sometimes my daughter is the more outgoing of the two and sometimes my son is. It is real fun when it is time to eat dinner they want to eat the same thing at the same time. All children are a blessing but I am seeing that it really is with our twins.


  7. Anastasia

    Hi! I’m the sister of a boy-girl twin. I have a twin brother named Colin. We fight A LOT, but other times; we really get along. Its satisfying to me that I have a twin. He’s a minute older than me. He’s sweet and generous, me and my friends aren’t ALWAYS nice to him, but he forgives me. I love his SO much! The main thing is, when you get older, you’ll realize having a twin is helpful and sweet. Hope this helped :)

  8. Susan E Johnson

    I am a twin, and I could not disagree more with the idea that being twins of different genders is without pressure or competition. You are still compared and contrasted with your twin by everyone in your life.

    1. Christina Baglivi Tinglof Post author

      Yes, you are right. I meant that same-sex twins are compared even more so.

  9. Reshmy Menon

    Hi, I am a mother of boy/girl twins. The article is so perfect according to my experience. My twins r 6 years and going to the same school and until now the same class. But next year they will get separated. The experience so far is the same as mentioned in the article, and for future I take those guidelines mentioned and try to be a good mentor, mom and a friend of both sex. Hmm,tough though but enjoying my life…!!!!

  10. thabile

    My 3mnths daughter seems like a month older than his twin brother but his brother have flexible and strong body.less

  11. Mike

    I am a father of a girl-boy twins toddlers, I came across this article searching for some guidance about the developmental discrepancies between my twins. I read that the girls would develop faster and be more assertive however we feel that she’s the one who’s behind, very passive letting him take her toys away, he shouts at her when he wants something she has and she just let it go, almost as if she’s afraid of him.
    Was wondering if this issue is at the root of a noticeable delay in almost everything compared to him, I know I should not compare since every child is different but I am trying to get all the facts I can gather.
    This is getting us worried.

    1. Christina Baglivi Tinglof Post author

      Realize that these articles are just generalizations and not every set of twins will follow. Perhaps your daughter is just more of a laid-back passive girl, or maybe your son is a bit more outgoing and forthright. But I think it would be wise to bring your concerns up with your twins’ pediatrician, especially when you say, “a noticeable delay in almost everything compared to him.” Do you mean just in personality or is there something more such as their language development? As I said, put your mind at ease and make an appointment with their pediatrician to discuss these issues at length. Good luck to you and remember, everything has a way of working itself out in the long run so try not to worry too much.

  12. Meredith

    I have almost four years old boy/girl twins. My daughter is like a head taller than my son. Do you think he will catch up to her one day? It’s no big deal but I worry about him getting teased at school later. No one can tell they are twins!

    1. Christina Baglivi Tinglof Post author

      I don’t think it’s a cause of concern as girls often tower over their twin brothers well into puberty! But just to put your mind at ease, I would speak with your pediatrician about it during your next visit.

  13. Kayla

    Well I’m the girl in a boy girl twin set and we will be 13 soon and unfortunatly I always feel like I wish we could ahve a stronger bond and do more things together but I feel like we are always an exeption to stuff people write online because he has autism so we go to different schools and he sometimes just doesn’t want anything to do with me gets out of controle I sometimes just wish we could enjoy being int he same school and doin homework together and so on.

    1. Christina Baglivi Tinglof Post author

      There’s always next year or the year after that. Never say never! Your brother and you may enjoy a strong bond as you get older. You are only 13 and although you sound very mature and insightful for your age, you are young, and you and your brother have your whole lives ahead of you! Is there something that you have in common, even something small that you could build on? Even if it seems small to you — something like a favorite movie — it will give you a place to start connecting. Don’t give up on the relationship just yet.

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