Is this normal for 3yo twins or are they really just brats?

Today my 3yo twins put a toy in front of a dresser in the room, climbed it and pulled the desitin off the dresser. They smeared it all over the wall, part of a medal bedframe, a blanket, and their faces were completely white along with their arms and had it on their clothes, and got it over my work jacket. Of course they got yelled at, and had to help clean it all up. My mom is going on about how bratty they are and claiming me and my siblings never did anything like that saying they're nothing but brats. I told her it's a typical 3yo thing and with discipline they would outgrow it.

Is this a typical 3yo thing or are they just brats?

Just an edit to add, they tagged teamed and moved a toy over their dresser and stacked things in top to reach the top of the dresser where the desitin was with their diapers and wipes. They were only alone for maybe 15 minutes while I cleaned up the kitchen and they were to be napping.