What's so attractive about thigh gap?

Why do almost all guys find thigh gap attractive?

I have one friend who can't stop starring at my thigh gap from behind. I figured some of my other friends also does the same secretly and some guys at school mention such things that they find it so cute.

Personally I don't care but I want to know how guys think about such things.

I don't see girls talk about it or stare at other girls, why do guys stare there a lot and say it's cute / attractive?

What's so attractive about thigh gap?
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