When Cooper Hanson’s mother is being honest with herself, this is what she admits: She no longer cares whether her eighth-grader is cold when he goes to school wearing his preferred winter outfit of shorts, a T-shirt, and — maybe — a fleece.

“There came a point where I stopped worrying about him freezing to death, and started worrying about how this would make me look,” said Karen Hanson of Danvers. “His actual health is secondary. It’s what are people going to think of me as a mother?”

image for cold weather

They live in New England, but they are living the French maxim: Il faut souffrir pour etre belle — one must suffer to be beautiful. Or at least macho.

“You feel like a bad parent,” said Dennis Gaughan of Natick, the father of a sixth-grader, “until you see them all lined up after school wearing shorts.”

Why does a person who owns warm clothing act as if he could not possibly understand its purpose? Perhaps the scantily clad Cooper Hanson, 14, put it best.

“I don’t know,” he said. “It’s usually just what I pick out in the mornings.”

Plus: “I don’t usually get cold.”

In Brookline, shorts-friendly 10th-grader Nat Bohrs, 15, also has reasons for exposing his legs in January.

“I hate jeans,” he said. “In shorts, I can move my legs instead of shuffling.”

Plus: “My legs don’t get cold.”

Sophomore Nat Bohrs walked in shorts to Brookline High.

WENDY MAEDA/GLOBE STAFF

Sophomore Nat Bohrs walked in shorts to Brookline High.

Statistics on the shorts-in-winter trend do not exist, but Marshal Cohen, a fashion-industry analyst with The NPD Group, said the style has become the way for boys to try and look cool in winter.

“In my generation, it was ‘Don’t wear a coat,’ ” Cohen said. “Then it was ‘Don’t wear gloves.’ For this generation, it’s ‘I’m wearing shorts all year-round.’ ”

Some parents fight the good fight every single morning and insist on wardrobe changes. Others report that with deep breathing, the encouragement of a more detached spouse, or an aggressively Zen attitude, they have come to accept it.

In Jamaica Plain, Alex England, a nurse practitioner with a seventh-grader who dresses for pleasant weather year-round, said her attitude has evolved. “I’ve encouraged him to dress warmly, but if he decides not to, that’s his choice.”

At this point, she added, she almost does not want him to take a jacket since she knows it will not be worn.

“My fear is that it would end up in the lost-and-found, never to be seen again,” she said. “Then I really don’t have anything if it gets cold.”

But then, what is cold?

Let us let the philosopher of shorts, Kyle Hency, take it from here. Hency, a cofounder of Chubbies, a San Francisco-based shorts brand with a party vibe and a manifesto, calls shorts a “state of mind.”

Even if it is Tuesday, Hency explained, “It’s weekend time. You are rocking these shorts. You are in chill mode, where it’s just you and the world, and you don’t have to listen to anyone — you don’t have teachers, you don’t have a boss, you don’t have parents.”

Alas, back in the real world, many boys of summer do have parents, and they sometimes worry about frostbite, as ridiculous a concern as that sounds.

But could the boys be telling the truth when they say they are fine?

Maybe.

Matthew Decker, a “comfort scientist” for W.L. Gore, the company that makes Gore-Tex, said that beyond a desire to look “macho,” boys have physiology working in their favor.

Because of differences in body fat, males do not get as cold as females, and kids and young adults are generally warmer than parents, he said, meaning that on average, boys may in fact feel the cold the least, and moms the most.

Here is why: Feeling cold has less to do with changes in a person’s core temperature than in changes in skin temperature.

“This is never popular to say,” Decker said, “but a number of studies have shown that, on average, females have 10 to 15 percent more fat than their [same-age] male counterparts.”

That layer of fat sits between thermal receptors that lie right below the skin — and control whether a person feels warm or cold — and the core of the body.

“The fat is effectively an insulator keeping the warm temperatures inside from getting to the skin,” Decker said. “That means skin tends to get colder on women faster than on men.”

But, as one mother observed, young males do not always enjoy warming benefits. Michelle Fournier, an owner of the Durty Harry’s dog boutiques in Charlestown and Brookline, noticed that her lightly-dressed 15-year-old is mysteriously comfortable waiting for the school bus in shorts, but feels winter’s bite at home.

“When I ask him to walk the dog,” she said, “suddenly he’s cold.”

Meanwhile, despite isolated reports of girls wearing shorts, Cohen, the fashion analyst, said they tend to go in the opposite fashion direction, constantly wearing Uggs, for example.

“They wear shearling boots all-year-round,” he said, “even in the summer.”

Nat Bohrs says his legs don’t get cold, even in January.

WENDY MAEDA/GLOBE STAFF

Nat Bohrs says his legs don’t get cold, even in January.