Stretch Marks in young male

by Mec

Hello, I have developed unnoticed stretch marks in my buttock area (on both legs) on the outer face.

I am surprised as I had not noticed them developing until they have installed themselves. I have read that sometimes these are caused by (illegal) use of hormones for growth, namely anabolic steroids and human growth hormone HGH. Yet I have not used any of those, having been a healthy sports guy.

Could it actually be from eating hormone enhanced beef or would that be stretching my reasoning too much (pun intended ;-) )?

Would it be a genetic predispostion to these? Or perhaps a normal consequence of stressing the skin while doing regular sports (like basketball and track and field)?