My youngest son grew up the other day. He is now officially taller than I am.

I knew this was coming. If you are a mother of boys, it’s a near certainty that you will one day be the shortest in the family. My older two sons are now nearly six and eight inches taller than I am respectively, and Alex—the last of the three—is 13 years old. It’s been all hairy legs and oversized feet for some time now. Nonetheless, I’m surprised to find myself here, looking up at all of my children. And I wonder how this new perspective changes things.

They’re not men yet, I know, even the 18-year-old. For one thing, their brains have not caught up to their brawn. Their insides don’t match their outsides. I say this lovingly, but with certainty since I write about the brain for a living. The revolution in brain imaging of the last few decades showed that it will take until they are in their 20s for their brains to fully develop. According to Jay Giedd, who has led this work, the last brain area to come online handles “the ability to inhibit impulses, weigh consequences of decisions, prioritize, and strategize.” These findings give one pause when you contemplate the societal rule changes and rituals that come at 16, 18 and at 21. And it will be fascinating to see the results of the National Institute of Health’s recently-launched Adolescent Brain Cognitive Development (ABCD) study, which will follow 10,000 children from 9 or 10 into adulthood, providing evidence on the effects of drugs, alcohol, concussions and screen time among many other things.

No Rite of Passage

But back to being thirteen. There is no rite of passage to mark the moment when you are taller than your mother for the first time. Alex first stood heels to the kitchen wall, his father wielding the tape measure. Then Alex and I stood back to back in our socks while his dad said, “Yup. He’s got you.”

I was reminded of the day, some five years ago, when I turned to reprimand my oldest and had to lift instead of lower my gaze for the first time. We were standing outside his room. I can’t recall what he had done wrong, but I can see Jake’s body filling the door frame even now. And I can feel my surprise and uncertainty at the subtle shift in the balance of power. What would I do if he didn’t listen? Did he feel it, too? I didn’t want to let him see it in my eyes. Teenagers sense fear, I’m pretty sure. I had to remind myself that my authority lay in my status not my size—as indeed it always had.

I’ve had time to adjust since then. When they leave the house, for instance, I make them tip their heads down to my level so I can plant a kiss on top (close to the top anyway). But there’s something visceral about relative size. So much of parenting when they’re young is about nurturing, cradling, protecting. The ability to swoop them up into your arms or snuggle them on your lap requires that they be of swoopable, snuggable size.  It can be terrifying not to be able to protect them physically in the same way. On the other hand, after years of me schlepping and lugging on their behalf, they now schlepp and lug on mine.

Passing of the Guard

My husband, Mark, feels their growth as a passing of the guard; it’s not just about height, but strength and speed, too.  Mark is inordinately fit for a 51-year-old, but when he and the boys are playing basketball, Jake is pretty good at backing his dad down under the post, and Matthew, now 15, can jump and hit the rim. They’re already taller than their father, and they’re gaining on him in every other sense, too.

In the boys, I sense occasional pangs of wistfulness for the little kids they used to be. They know that growing up in inches brings them closer to the responsibilities that will come with being actual grown-ups. Mostly though they are gleeful about their height, and with good reason. (They’re not just taller than I am, they’re taller than average.) An early growth spurt and being tall in high school has been shown to help a kid navigate adolescence. A study of more than 14,000 teenagers found lower rates of depression and higher self-esteem in tall teenage boys. In his book, Size Matters, journalist Stephen S. Hall compiled convincing evidence that your height at 16 determines how much you are paid in adulthood.

As for me, I now aspire to be a maternal Yoda, small, but wise and indispensable, regularly reminding my boys to use the force they’ve been given for good. I tell them to challenge their brains and their bodies, and to continue to grow emotionally and intellectually. And when I have to, I remind them that they’re not in their 20s yet, and that I know exactly what’s happening in their heads.

This post originally appeared in my Brain Waves blog on PsychologyToday.com.