I'm not necessarily trying to disagree with folks here, and yes, i don't have kids, but i'm always amazed when i see kids at the beach (or other water sources) in the early season, etc, braving, and apparently tolerating or even not noticing cold water that most adults except the far northern Canadian folks, won't even think about getting in. I've seen this too often to not notice and wonder about it.
Seems like kids furnaces burn hotter as a trend, and maybe also something about the mind aspect seems to change things for them. Kids generally aren't so full of such strong and concrete belief systems about how things should be and are, and i think in some ways that works in their favor, like at the beach or streams, lakes, etc.
But yeah, i'm not saying don't well insulate your kids, just wondering about the above and how it fits into the scheme of things.
Course, there is the well known case of the wild French boy. "Experts" say that humans are just not physiologically adapted to cold weather innately (which seems obvious physically), and yet they can't adequately explain cases like him, Wim Hoff, some of the Tibetan monks, and others. For those who don't know, the case of the wild French boy, well even after they tried to "civilize" and culture him, he still had a penchant for frolicking naked out in the snow.
Perhaps to some extent, our minds and beliefs or lack have more of an influence than we tend to give credit for?