What do you do if you're getting married and your parents and the future parents are chalk and cheese?

What if the very thought of them being in the same room terrifies you?Example Stepfather thinks he is a phsychologist..ysing anyone that moves..Mum is a free spirit, who loves swearing and scotch..Father-in-law is straight laced man, no bulls*** man,very set in his ways,man of few words...mother-in-law is law abiding christian frowns upon drinking, smoking swearing, anything she doesn't approve of..and thinks her son is still2 and needs his bum wiped.Help!!!!!!