Stretch marks . WHY? 😖😖

I am for not a second saying stretch marks are ugly or anything as they are not and are natural but i was checking down there and noticed that my thighs have got LOADS of stretch marks in between, I haven't been putting weight or anything and I don't understand why I have them? I know it's natural but why? I don't like them on my self especially how dark they are, could anyone help me? How can I get rid of them ?