How do you keep really cute kids humble?

I have two boys 9 and 7 they are ALWAYS getting attention on their looks. They have a pretty rare set of features, carmel colored skin with forest green eyes. They both have matching curly mohawks also that may draw attention. Also, I'm white and my wife is black so that also might draw attention but it's just ridiculous lately. A normal walk in the mall and we will get stopped several times by people telling us how cute the boys are. Today we counted how many times strangers and family members brought up the boys looks. It was 14 TIMES by DIFFERENT people. One women in Vegas last year (when the first got mohawks) even asked for a picture, I mean WTH? I didn't mind much, but it's going to the boys heads. They think they can get out of anything by being cute. I watch them manipulate my relatives with ease. On christmas they are swamped from both sides of our fa miles. Favorite grand kids, favorite nephews, favorite cousins! I don't want my boys to grow up and be conceited. I don't want them to be full of themselves. My 9 year old is already starring in the mirror a lot, working on his "six pack," worrying about how many "girlfriends" he has etc. What are some things I can say or do to keep them level headed and not conceited about their looks?