Growing Up on Different Clocks

Teen boys and girls are not developing at the same rate.

Summer is my time for reading, and truthfully I only read non-fiction. This year I happened upon The Collapse of Parenting by Leonard Sax, and it put words to patterns I had been circling for years, both personally and professionally.

What grabbed me most were the gender dynamics. The boys and girls, and sometimes their parents, coming into my office are having such different experiences and ending up in such different places that it is hard to believe they grew up in the same era under the same expectations.

I tend to go in spurts with an author. When someone is asking the right questions, I will often read some or all of their other books to get a deeper picture into their research. Sax’s unique training, got me so interested that I spent the summer working through his other works, including: Why Gender Matters, Boys Adrift, and Girls on the Edge.

That comparison is where the value is. A book by itself is an argument. A book read against a caseload of thirty clients a week, against what I see in my own community, starts to look like a diagnosis.

As I mentioned, Sax has a unique perspective and background. He holds a PhD in developmental psychology and an MD from UPenn, and he practiced as a family doctor for more than twenty years. Most people writing about kids are either researchers who never see patients or clinicians who may not read the research critically. He does both. He is blunt, sometimes uncomfortably so, and he helped me find a stronger voice for what I have been seeing.

Here is the short version of what I took away.

Girls Are Starting Earlier

Puberty in girls, meaning the early signs such as breast development, used to begin around age eleven. That is what the old textbooks said, and for a long time it was true.

It is not true anymore. Girls today commonly show the first changes around age nine, and for some groups earlier.

One study Sax cites stuck with me, because it argues against the easy explanation that this is just about girls being heavier. Researchers in Denmark compared girls studied in 1991 with girls studied in 2006. In fifteen years, the age at which breast development began dropped by almost a full year. The age of first period changed far less.

That is a strange result, and it matters. If this were only about better nutrition and higher body weight, the whole sequence would slide earlier together. It did not. Something is flipping the first switch without moving the rest. That is exactly what you would expect from an outside chemical acting like estrogen.

The practical result is that girls now spend two to four years in a long, drawn-out early puberty. Their bodies look like a teenager's. Their judgment is still a fourth grader's.

Boys Are Not on the Same Curve

Sax argues in Boys Adrift that the same chemicals speeding girls up are doing something different to boys. Many of them act like estrogen or block testosterone. In a girl's body, that pushes the system forward. In a boy's body, it works against him.

I want to be straight with you about this one, because it is the part people overstate. The data on when boys start puberty is mixed. Some studies show boys starting slightly earlier, not later.

What is clearer is what happens after they start. Testosterone levels in American men have been falling generation over generation, in a way that aging and general health do not explain. Men today have less than men of the same age did decades ago. Sperm counts have dropped sharply over the same period.

So the picture is boys starting on time and finishing weaker. The engine turns over. It does not produce the same power.

That matches what I see and hear. I meet boys and men, or the girlfriends or wives of them, who went through puberty on time but came out the other side without the drive that is supposed to come with it. Moreover, I have young men who were so endulged that getting a job would make them “normal”, and yet they are living at home well after college… How do these boys learn mastery, and become men or father’s ever hard-charging girls and women can rely on.

Where the Chemicals Come From

The compounds we are talking about are in ordinary places. BPA is in some plastics, in the linings of cans, and on receipt paper. Phthalates make plastic soft and carry the scent in most fragranced personal care products. These are not exotic exposures. Testing has found BPA in the urine of the overwhelming majority of Americans.

I am not going to pretend you can scrub this out of your child's life. You cannot. You can heat food in glass instead of plastic, cut back on canned food, buy fragrance-free soap and lotion, and skip the paper receipt. Do those things. They help a little. Yet, they are not the answer.

The screens are the part you can actually control, and that is where I want to spend the rest of this.

What Meta Just Told Us Without Meaning To

On August 26, Meta agreed to pay about $17 billion to settle claims brought by the attorneys general of all fifty states. The lawsuit said the company deliberately designed Facebook and Instagram to addict children, tracked the harm internally, and did not tell parents.

Look at when they settled. Not before the trial. In the middle of it, days after the head of Instagram had already taken the witness stand. Meta had spent years calling these claims unsubstantiated. They had a full defense underway. And they stopped it and wrote one of the largest checks of its kind rather than let the jury hear the rest of the evidence.

Companies do not do that when they think they are winning.

Of course, despite this settlement, Meta admitted no wrongdoing, and their lawyers will tell you settlements are routine. I do not buy this argument at all. You do not walk away from a trial you are winning. You do not agree to hard daily time limits for minors, nighttime shutoffs, and age verification as a matter of housekeeping. They could have done this from the very beginning. The only version of this that makes sense is that what information had yet to be presented in the courtroom was bad enough that $17 billion was the cheaper option.

And this came after they had already lost in New Mexico, where the court ordered them to pay more than $900 million. I beleive history will look back at this moment similar to the first landmark cases that took down Big Tobacco.

Think about what that means for the argument you have been having with your kid about their phone. For years, parents who raised this were told they were anxious or old-fashioned. Everyone was getting phones in 5th grade. It is ok if they stare at a phone all day and never interact “IRL”, in-real-life. That is over. Meta was a first class predator. It built the machine, measured closely the adoption, what it did to children, and has now paid an enormous amount of money to keep those measurements from being read out loud.

So Take the Screens Down. Really Down.

The reasearch Sax presents has given volume to the feelings I have had regarding screens. He reminds readers that executive function is the ability to hold a goal, sit with boredom, resist an impulse, and keep going after something stops being fun. It is built slowly, and it is not finished until the early twenties.

Do the math. If a girl's body arrives at nine and her brakes are not installed until twenty-two, that is thirteen years of gap. Somebody has to be the brakes during that stretch. There is no candidate for that job except you.

Screens attack that gap at its weakest point. If you change nothing else after reading this, change this one. Not a cutback. A real curtailment. Phones out of bedrooms overnight, every night, no exceptions. Hard limits on gaming that you enforce instead of announce, meaning 1-2 hours a day max, no roll over time. No violent video games and screens in a family area, where all can see. Social media pushed back as long as you can stand it, especially for girls, or while they are under your roof, and this may need to include kids living at home during or after college.

You will be unpopular in your own house. That is the job, especially if you really want them to meet their potential.

If you have more questions on when to give a phone or increase autonomy with screens; Here is a link to a test. It will help you start thinking about your child’s phone/media readiness, because it is not a hard and fast rule and each child is different. Note: Readiness is domain dependent and specific to each children. Generally though, researcher and therapists have built a concensus—no smart phone earlier than 16 and no social media until 18 is best for overall mental health and identity development.

Boys and the Reward System

Video games are not a hobby that got out of hand. They are engineered products, purposefully built by people who understand how the brain operates with scarcity and reinforcement better than any parent does. It is built on knowledge developed by the gambling industry. (Note: Read the Scarcity Brain by Michael Easter, if you want to know more.)

Researchers scanned people's brains while they played a video game and found dopamine release in the reward centers on a scale comparable to what you see with stimulant drugs. That study came out in Nature in 1998, and Sax builds much of Boys Adrift on it. The rewards are also deliberately unpredictable, which is the most powerful reinforcement pattern that exists. Loot boxes and battle passes are not accidents. They exist because the psychology is well understood and profitable.

A boy whose reward system is getting flooded that way has no reason to put up with the slow, frustrating work of getting good at something real. Why grind through a season where you might sit the bench, or a class that pays off in five years, when the same brain chemistry is available in twenty minutes for free?

This is the boy who is not depressed, not in crisis, and not going anywhere. He is not lazy. His motivation system has been captured by something better at stimulating it than his real life is.

Girls, the Mirror, and the Sports That Are Also Mirrors

For girls it works through a different door. Social media does not mainly hijack reward. It hijacks the sense of self.

A girl on these platforms from a young age spends the years when she should be building a self building a product instead, tuned constantly against feedback from an audience. Sax says this hard in Girls on the Edge: a girl can look excellent on every measure you can score and be hollow underneath, because nothing in her week has asked her who she is when nobody is watching.

Here is the part that usually gets missed. A lot of what parents pick as the healthy alternative works the same way.

Cheerleading, dance team, figure skating, gymnastics, and ballet are demanding and disciplined and often genuinely good for girls. But they share something. They are judged on how the body looks. The body is both the instrument and the scoreboard. There is a mirror on the wall for hours every week. That is why these particular sports show consistently higher rates of eating problems and body image trouble than other athletics do.

Now picture a girl in that world at nine, when her body has already started changing, with a phone in her hand. She is judged on appearance in the studio and judged on appearance on the screen, with no space in between. There is no part of her week where she is valued for something you cannot see.

That is what is getting squeezed out. Girls need something in their lives that is theirs, that nobody scores. Time outdoors. Service to somebody else. Faith practice, if that is your family. Music or art made badly and privately. A friendship that is not performed for anyone. These are not enrichment. They are protection, and they are the first things to vanish when the calendar fills with judged activity and the leftover hours go to the phone.

If your daughter is in one of these sports, I am not telling you to pull her out. I am telling you the sport is not the protective factor. It may be one more mirror. She needs one place a week where nobody is looking.

Why They Seem So Far Apart

Put the two paths side by side and the disconnect explains itself.

By middle school, girls are two to three years ahead of boys physically and socially. That gap is not new. What is new is that it widened at both ends. Girls arrive earlier. Boys arrive with less push. And both are spending their formative hours inside products designed to hold attention rather than build a person.

Girls that age want something back from boys who are not there yet, so they reach for older boys, and that is where most of the risk lives. Boys feel they cannot meet the demand and retreat to video games a place where they feel a sense of mastery and control and are guaranteed to be good at something.

Fast forward ten years. Young women are ahead of young men in high school completion, college enrollment, and college graduation by a wide margin. Fewer are pairing off. Young women say they are looking for partners who are not there. Young men say they do not know what is being asked of them. Both are telling the truth, and it started around age nine.

I believe this is part of what is driving lower marriage rates, women in their forties unable to find a suitable match, and rising numbers of single-person households.

Parents: What Your Job Requires

A girl whose body shows up at nine needs more supervision, not less, and adults who keep insisting her worth is not located in how she looks or what she does.

A boy who is drifting needs real demands from adults who are not afraid of making him unhappy. He needs real friends in real life who challenge him and whom he can compete with. Dads need to step up. Boys need to leave the mother's sphere around age ten or eleven and be welcomed into a sphere of healthy adult men, and to spend time in the physical world where effort and results are actually connected.

And both of boys and girls need the adults to take back the ground that got handed to peers and devices, especially in puberty. You have to be their co-regulator while their brains do not have the ability to do it. It is a tough job, it is challenging, it sucks at times, and it requires a level of unrelenting vigilance if you want your kids to meet their potential. I tell parents, food and screens will be a constant battle until your kids leave the home, or until you have thoroughly taught them to self regulate with them and make healthy informed choices.

This is authoritative parenting, the best-supported style for raising resilient kids. It is a combination of hard and soft: hard boundaries and structure, along with warm unconditional love, the soft place to land. That is the central argument of The Collapse of Parenting, and your child’s entrance into puberty is what makes it urgent. The years when kids need adult structure matters more now, because the gap between physical and mental maturity is widening, and in some cases the maturity is not showing up with the same vigor. Ignore that and you should get ready for the boomerang, or the failure to launch.

Where Next?

If you read one of Sax's books, start with The Collapse of Parenting. If you have a son, read Boys Adrift next. If you have a daughter, Girls on the Edge. Why Gender Matters ties it together.

Read him critically. He is more certain about some things than the evidence really supports. But he is asking the right questions, and in my experience the questions matter more than the certainty.

The books

Leonard Sax, The Collapse of Parenting (2016), Why Gender Matters (2nd ed., 2017), Boys Adrift (rev. ed., 2016), Girls on the Edge (rev. ed., 2020).

The three studies mentioned

Aksglaede and colleagues, "Recent Decline in Age at Breast Development: The Copenhagen Puberty Study," Pediatrics, 2009. The Danish comparison.

Travison and colleagues, "A Population-Level Decline in Serum Testosterone Levels in American Men," Journal of Clinical Endocrinology and Metabolism, 2007.

Koepp and colleagues, "Evidence for Striatal Dopamine Release During a Video Game," Nature, 1998.

The Meta settlement

Reported August 26, 2026 by NPR.