Kelly Matthews

I know this is a really wierd question but is it possible to grow glutes like Kelly Matthews? She rarely posts her before glute pictures so I am a bit skeptical to know if those glutes are completely growm due to just workouts. She lifts very heavy and maybe I lift one-third of what she lifts but my glutes seemed to stop growing even with progressive overload. I might need to change my workout pattern.

So, my question is did she begin with a good foundation on her glutes or did she have a pancake butt in the beginning? Are those glutes developed only through exercising?