At least that means he's not just into you for your looks.

Awww he didn't validate you?

Deserved. Asking loaded questions makes you seem like a douchecanoe. They're a red flag to guys.

at least hes honest ....

yea... would you rather him lie? now you know he'll be straight with you; so if he bangs your sister at least he'll tell you if you ask

I'm with #5

Translation: Your sister is prettier than you are, but he met you first / isn't good-looking enough to get with her. Bottom line is that he's into YOU. Not her.

Never ask someone that question unless you're prepared for the truth.

Agreed with #5

This strikes me as the guy actually not thinking your sister is prettier at all, but trying not to disagree with you. It could very well be that he thinks you're the more attractive one by far, but he just doesn't want to disagree. And frankly, it really doesn't matter if he thinks your sister is prettier. I will admit plainly that there are plenty of girls who are more attractive than my ex (whom I still have feelings for), and would have admitted this even when we were dating. But honestly, that doesn't make a difference - I would take her over any of them any day. If he's interested in you for more than mere looks, it doesn't matter. If he is only interested in you for your looks, you're better off without him - even if he does think you're the prettiest.