Do you have a younger daughter who’s bigger than and bullies an older son?

Don’t blame the size difference before you look in the mirror as the cause.

There’s a thread on a health site explaining that the girl is nine years…but 5-5 and 120 and shows signs of puberty. The son is 13, five feet and 90 pounds.

The post describes the son as depressed, and that he and his sister occasionally get into fights and that she is stronger “and can hurt my older son.”

The second case from involves a 16 year old boy, 5-5, and his 14 year old sister, six feet.

The parent writes that the girl regularly inflicts physical harm to him.

I used to be a certified personal trainer for a large gym. My knowledge of physical fitness, muscles, force exertion, etc., tells me that the nine year old girl — as a general rule now — cannot possibly be stronger than a 13 year old boy.

Never mind the height difference; his body is 13 and her body is only nine.

Long bones and long muscles don’t translate to more absolute strength. Let’s call her “Sally” and him “Jack.”

Unless Sally has a bizarre medical condition that has caused her to acquire teenage musculoskeletal development at age nine, I very strongly doubt that she could bench press more weight or throw a harder punch than a same-age girl of “normal” height.

Shutterstock/F8 studio

Though Sally would find it easier than her female classmates to, say, place a 15 pound box on a six-foot-high shelf, this is only because of her positioning — her start position has her vertically closer to the shelf.

But this isn’t a display of absolute strength. An example of absolute strength, rather than mechanically-advantaged strength, is that of pressing a force away from your body.

Though a longer arm should have more torque than a shorter arm, and thus in theory should be able to land a harder punch, I have not seen evidence of this in all the years I’ve studied martial arts.

Due to his age, Jack has more developed muscles, bones and neuromuscular connections.

This would make him stronger in the absolute sense. But psychologically, Sally has him pummeled.

I’ve worked with short strong clients and tall “weaklings.” For instance, I’ve had tall clients struggle with pushups.

So then, what’s going on when the smaller son gets beaten up by his younger, bigger sister?


The shock value that Little Sis is so much taller may create the illusion that she’s stronger.

This may intimidate the older brother who already has a pre-existing low self-esteem stemming from unhealthy family dynamics.

One day Sally gets mad at Jack and shoves him. Her towering height scares him; he concludes she’s stronger; she comes to believe this based on his fear; she continues pushing him around because she thinks she’s stronger.

(I wonder which of these kids Mom tells to take out the heavy garbage—I’m betting the son.)

I’m betting Jack would find it easier to bench press an empty Olympic bar (45 pounds) than would Sally.

But there’s a big power imbalance going on that’s based on psychology, not muscle fibers.

Haven’t you yourself ever witnessed, when growing up, situations in which the bully was smaller than the victim? I certainly have.

Even in the adult world, the “bully” is sometimes smaller than the victim.

It’s akin to the feisty cat scaring off the much bigger dog.

In the second example, the six-foot-girl might be stronger than her slightly older, shorter brother because she’s already 14.

Maybe she’s a jock; maybe the brother, only two years older, is a bookworm.

A child or teenager will not automatically become a bully to an older sibling just because the older sibling is a lot shorter!

If being bigger than the older sibling is indeed all it takes to turn a child into a bully…then nearly every teen or child with a smaller but older sibling would be a bully.

Size differences do not create bullies! Size is only a tool that the bully realizes she has!


–     Get to the root of the sibling bullying instead of blaming it on the superficial feature of size difference.

Could it be your own behavior that’s setting a poor example? Bullies don’t always spring from a physically abusive parent.

For example, “What is more likely, is that children who bully have witnessed their parents use bullying tactics on others,” explains Rona Novick, PhD, developer of the BRAVE bully prevention program and a clinical psychologist.

“They may see Mom or Dad abuse their power to get their way with waiters, dry cleaners, teachers, neighbors or other family members.”

–     Reassess your typical response to the fighting between your younger, bigger daughter and older, smaller son. It’s obviously not working.

“Scolding is not the best remedy; humiliating a child only escalates the behavior,” says Janet Lehman, MSW, co-creator of The Total Transformation Program, a program for empowering parents.

“The best approach is to clearly identify the behavior: Label it, communicate that it is unacceptable and attach a clear consequence for the rule breaking,” says Lehman.

–     Enroll both kids in martial arts. The bully will mellow out and learn self-discipline, and the victim will learn self-confidence and have tools to stop a fight with minimal physical force.

–     Telling Sally to be nice to Jack because she’s probably stopped growing, but he hasn’t yet reached his growth spurt and will be bigger and stronger than her in a few years, won’t correct the underlying problem.

Dr. Novick is recognized for her expertise in behavior management and child behavior therapy. She has published scholarly articles on school applications of behavior management, children and trauma, and bully prevention in schools.
Janet Lehman, with her husband James, developed the foundational parenting programs offered by
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  
Top image: Shutterstock/Black Rock Digital
Sources: and: