I am having a normal fatted hip. But my thighs are too big. What's the reason for it. Is it possible to reduce it?

Genetics controls a lot of our shape, and our rearing and present day habits control the rest. You could try anything from brisk walking to pilates and yoga to tone your thighs and lose some inches, but like a lot of us, one part of the body may always be disproportionate to the rest.