Why do kids walk so loud!?!?

I have a few siblings, oldest is 10 and youngest is 7. I live in the basement (not that kind :P it is very developed) but every time the kids run across the house I could freaking swear they're purposely stomping!! It's like when they walk they slam their feet flat on the ground!! wth??? I walk basically on my toes trying to make the least noise possible, why do they do this? will they grow out of it? It seems like a very inefficient way to walk by all means! lol