From an outsiders perspective, this sounds like the perfect time to show them what you're made of. They are probably collectively insecure that someone younger than them has already accomplished more than they have at that age, that's all.
Since you all banter together, I don't think it would be out of place to shut down those jokes by playfully poking that nerve on purpose! You could get away with retorting that you bet they didn't get ahead faster in school because they are lazy and repetitive (jokes about ethnicity and age are so obvious... ). Then you're someone to be reckoned with, because then they realize you're okay with using bigger guns. You also then stand your ground as someone who values being NOT lazy and NOT repetitive.
Every time they use those same jokes, you can just use it as ammo, as proof that they're repeating themselves again and ultimately being a joke themselves (my sadistic streak is really coming out wow). Then bam, they respect the crap out of you for being totally awesome and slay their butts at banter. In theory.
However this is definitely more provocative and offensive, and not what you asked for in your post. But it IS your trump card you can use at any time to shut down anyone, so just remember you have the perfect flexible defence for any bully type situation. So feel confident. Just don't become a bully yourself with it!
Alternately to approach this with more subtlety, I agree with the user who suggested body language and protests. You can also be dismissive and melt any joke by not being offended and saying that you are totally cool with those things about yourself, which to be honest are quite normal and unproblematic features of a person...
"If you have a problem with white, younger people, then North America is not for you" comes to mind!