My best friend has a downright sexy, gorgeous little sister. Straight up, not sure how they are siblings considering how stunning she is. Anyways, he's extremely protective of her since she is his little sister, never wanted me or any of our close friends messing with her, etc. Hell, he even barged into her room one time after he asked where I was and our other friend said I was in his sister's room, when in fact I was only using the restroom...
Anyways, long story short, she's currently my wife. I'd say go for it as you never know if you don't try.