Are your glutes and hams as developed? If i'm right they shud be more developed..
edit more explanations --
1. Your quads show development consistent with a person who does 475lb paused back squats regardless of style
2. Not to say you use zero quads in your style, it's def more than someone doing a LBBS say, but not as much as someone doing a TK style olympic squat
3. You were born with them you haven't acquired them thru your backsquats (?)
4. If you used TK style olympic squats you'd have even more impressive quads
5. low bodyfat makes fools of us all
6. i'm completely wrong but i doubt it