Observing no.1 son grow up has, on many occasions, felt like undergoing a psycho-therapeutic exploration of my childhood. So many of his motivations and anxieties trigger memories of my own youth and the predicaments that my thoughtful but naïve younger being would self-inflict. And seeing my older son heading up cul-de-sacs of his own making would make me wish I could convey what I have learnt: making mistakes is uncomfortable but worth getting used to; doing something is almost always better than doing nothing (exceptions: sinking sand); you only look embarrassing if you are looking embarrassed.

I have never been unaware of the possibility that I am merely projecting my personality and motivations onto my older son. Approach a problem with a particular frame and you’ll see what you want to see. I believe, though, that I have indisputable evidence that this is not a solipsistic delusion. The most persuasive argument I can present is: no.2 son.

Four and three-quarters years younger than his older brother, the third and last of Mother in the Middle and my progeny, he clearly has different influences to the first born: the example of two older siblings, relatively relaxed and experienced parents, a busy household, a school and social life where for many he is so-and-so’s little bro’.

Yet, allowing for these environmental factors, there is an innate distinctiveness. When friends ask how the family is, I relate Mother in the Middle’s non-stop life and then for the children I will summarise the latest achievements of no.1 son and the 1&onlyD, then pause. “No.2 son, he’s just a [insert age] BOY.” That sounds belittling, but I know when I’m saying it, I’m shaking my head with wonder, trying but failing to encapsulate the essence of energetic, affectionate, noisy, charming infancy that he represents. Where his older brother and sister have been precocious, pushing some of the boundaries of their age, no.2 son exists comfortably within the developmental median for his calendar age. He’s a pup in no hurry to be a dog.

Mother in the Middle booked our summer holiday before last Christmas. The kids had months to speculate and build expectations of their two week stay in France in August: the pool, the tennis court, canal, river, pizzeria, beaches and French folk. One day, earlier in the summer, rain falling outside, the 1&onlyD was longing for this trip. It would be so good just to sit in the sun and read, we agreed. No.2 son heard us, expressed shock: “No. There’s a pool and a river, we’re going to be swimming, not reading.” We had, but really didn’t need, fair warning.

The first morning of the holiday, I woke early. I carried a chair, a book and a cup of tea out into the sunny garden. Minutes later, no.2 son was at my shoulder, asking for breakfast. Not many minutes after that, he was back, in swimming shorts.

Can we go to the pool? No. It’s too early. Will you play football? Not yet. And can you speak quietly, there are lots of people sleeping around here Ok. [withdraws, singing heartily]

Throughout the two weeks, no.2 son’s appetite for activity was continuous, and probably entirely consistent with that of a nine year old. In child- and adulthood, I have had a threshold where the desire for activity is submerged by a preference for comfort. Sure, I’ll play in the pool. But once I’ve dried off, getting wet and cold again has insufficient appeal. A kickabout in the garden is fun, but tea time means full-time, not half-time. No.1 son shows similar reservations and qualified commitment.

I admire and envy my younger son’s relentless pursuit of physical fulfilment. Another plunge into the pool, yet more charging after a ball in the garden, gymnastics with his sister if that’s the only action on offer. This physical boldness equips him well for sport: tackle after tackle on the football field; every time he gets the ball, a dribble past opponents or attempted defence-splitting pass; in goal, he bursts out towards attackers, diving at their feet; on the cricket field always closing in on the batsman, defying the coach’s instruction to take 10 steps backwards; sliding, sprawling to stop the ball hit in his vicinity.

Standing on the touchline, I see him play without fear. It is exhilarating, the most predictably exciting part of my week. And it’s disorientating, that a child with my genetic inheritance runs unencumbered by fear, the very impulse that has inhibited my every sporting fixture or active adventure.

He’s not tireless or immune to pain, but neither are reasons to stop. Activity is an end in itself. Comfort, reflection, quiet time are reluctantly accepted and usually attempted swinging from a chair, singing or chatting in a funny voice. A family friend once asked Mother In the Middle what it must be like for no.2 son to live in such a quiet family. It’s a good question.

Where might this boldness end? In A&E, Mother in the Middle worries, particularly when we’re on holiday. Our time in France, though, showed that it has its natural limits.

Sitting together on the flight, I tried to distract no.2 son’s anxiety of flying by reading and offering sweets. Twenty minutes after take-off, his hand still gripping my arm, Bilbo Baggins’ adventures were lost in the drone of the plane’s engines and no.2 son’s anxious inattention. A lady in the row behind tapped me on the arm. “My daughter wondered if your son would be happier with this,” handing me an iPad, headphones and a Pixar movie, which he used for the rest of the flight.

Shopping in France, there was a bouleversement in the supermarket. A known shop-lifter was being escorted out, against her will, noisily. No.2 son grabbed my arm and tried to drag me away from the till which the assistant was keeping shut while the incident was dealt with. “It’s a riot. I want to go. Take me out,” he implored.

Then there was the thunderstorm. Like flying (and dogs) it’s not an unusual fear for a nine year old. But, given his bullish, bold presence through so much of life, it’s a reaction that surprises me.

There’s one rather bland conclusion to this reflection about my younger son: that we are all complex beings with apparent contradictions at our heart.

Writing it down has helped me reach a slightly more sophisticated insight. It suits my shorthand image of my family that no.1 son is ever so similar to me and his younger brother a different animal all together. As a shorthand it holds a lot of truth. But as an appreciation of my children it short changes them and risks me under-appreciating where my older son is different to me (his ease in the company of adults, is a strong example) and the many aspects of my younger son where I can’t just sit back and say, “Wow, I could never have done that.” Difficult as it is to do, I would be better off keeping the comparisons to myself out of it.