Just plain rude!

it better to have a good relation with your fiance family. i wonder what will they say if you said this directly to them "hey, dont be rude. this is our lives and cultures. would it be okay if i ridicule your culture in return?"

Look, jerks exist, in every culture and every part of the world, and there is nothing you can do about them. You really can't wish them away, you know. You have got to accept that they are so and get on with your life. Pay no heed to them. The more you get flustered by them and show it, the more they tend to do to rub you the wrong way. Ignore them, and they go powerless. That quote about marrying the family is kind of right, but what can you do about it? If they were the understanding type, you could have tried to get adjusted to their way of life, even compromising on things you like, just to accomodate them, but when they are jerks like your in-laws, you just ought to be giving them the cold shoulder. You seem to have an understanding fiance. You could not have asked for anything more than that. All the very best with everything that comes your way. Peace and God bless!