You could say, too, that some horses just have a lot more energy to put into their time on this planet. Has anyone ever had the busy animal that is just more of everything. I haven’t found that sex or neutering changes things completely. I’ve had a boss gelding on my then farmette. He was a benevolent, older, Arabian who saw things that needed to change. The others were all younger and followed his lead.
I’ve also seen my grown to 11 year colt (mare’s foal) that had that same energy. He just had to be busy and still has his head in everything. My mare had to accept limits due to being a 14 3 Arabian in turnout groups, but she always had a great relationship with the boss. She was lively and bold to ride. Want to go on a solo trail ride at a new place, she was your girl. I had her since she was 3 until 14, and we worked through lots of stuff. She was always reliable, just like her colt. In her younger years, her take over behaviors were to get us out of Dodge if she ran across something spook/dangerous and that always included bringing her rider with her. As well as dropping some of her acting out around the barn, she matured into a lovely, accepting, get along type. She became a lesson horse for beginners, just like her half warm blood son who is my main ride these days.
I think it is the individual horse. As a kid, my starter horses were a hot grade horse (ex barrel horse), and off track Thoroughbreds, so that is the type I tend to know something personal about. They can need to be busy.