Do foals personalities change as they get older?

My first foal was born 8 days ago (at a repro Vet). They said she was extra reactive her first 24 hours - overreacted to light, noise, touch, etc. and they said she’s gettibg better every day. I went to visit her last night and she is a BRAT. She kicked the vet and the mare, runs away from her mom and seems to have no fear without her (doesn’t look at all while the mare screams for her). Definitely brattier than the other foals there. 

The mare herself is very calm with no personality. 

I was just wondering if babies are born with their personalities, or will it change? Seems like a dumb question, I know - but I have no experience with foals at all! I was just curious!

My filly is a little over a month old and was the same way when she was bone. She's still a brat but a little better. My mare is very laid back and hardly hollers for her. You have to think of them just like a child. They take a lot of time and patience. They learn from you and the mare. Mare with have her way of correcting her. I wouldn't say she will always be as reactive but you are also going to have to spend time to get her used to a lot of things. 

I think in some it changes in others it doesn't. Some personality traits are their own unique thing, some I can swear they got from their dam or sire.. especially if you have enough babies from the mare or from that sire. 

It sounds like what you're describing I would predict will get better once shes weaned and halter broke/handled. I think theres parts of their personality they keep from day 1 and parts of their behavior that can be modified with handling. 

My colt was so easy going and fearless over anything when he was a weanling. Still that way to this day, just a lot harder to move when you want him out of your space lol. Nosey is an understatment with mine.