Why both Sam and Dean where children
It always bothered me that Dean said not once, but twice that he was not Kid. The first time I hear Dean say it to Jo on season 7 episode 4 (defending your life) it made me sad for his lost youth but it also bothered me I didn’t quite understand why. Then when he said it, again this time to Mary in season 12 episode 14 (the raid) I had the exact same feeling as before and I couldn’t understand why I had that feeling, until today. I recently posted a poll on prank wars and most of you agreed that it would be awesome to have them back on the show. As I was thinking back to prank wars, I also thought back to the countless amount of times that Dean did childish things: laughing at a couple kissing, eating like a 5 year old, pudding, defying authority, losing at rock paper scissors because he likes rock, making noises when bored, prank wars (you can’t convince me that Dean didn’t start that)…..the list could go on and on, but basically all of the earlier seasons is a great sum up. It is impossible for someone with that massive amount of creativity, and energy not to have ever been a kid.
It was then I understood why it bothered me. It bothered me not because I thought that he didn’t have a hard childhood or because I thought he didn’t have to grow up way to fast (which by the way I believe he did have both a hard childhood and that he grew up way to fast). It bothered me because he was a child in every sense of the word.
Someone who is never a child or allowed to be a child doesn’t know how to play how to be a kid. Countless studies have shown how technology is robbing our youth of their ability to imagine and play, because they spend more time behind a screen. Nobody is going outside getting dirty, running, jumping, etc. Part of it is society, part of it is safety and part of it is convenience. The bottom line is most kids don’t know how to be kids.
Dean however does, and not because Mary let him be a kid while she was alive, but because he got to be a kid growing up. He had a lot of responsibility, but he also got to have fun to be a kid to test the boundaries, to act up. He did all that he was more of child than the children of our current generations are. He was a child because he got to be a child, just not freely and consecutively, and yes, it’s a shame, but he did have a childhood in between hunts or being in charge, he was. He had to be and for a very long time after all “childhood amnesia”, a term that defines an adults lack of ability to remember things before the age of seven, wouldn’t have let him remember things concrete with Mary just bits and pieces.
So yes, both Sam and Dean were kids and had a childhood. Sam’s being richer than that of Dean’s but they both got to be kids and that is cannon.

https://psychcentral.com/news/2014/01/26/whats-your-earliest-memory/64982.html