There ARE similarities with different cultures, yet the very daily Human effects upon this planet and across cultures must be accounted for in ANY STUDY. That is a DAUNTING TASK!!!! I just wrote a bit on Gerda's other Post on Inner Space, about the investment of mind toward a personal slant of ideology. There is a rule of thumb I quote, which is from years ago:
"Our differences are our similarities". It is just and true that the multiplicity is a treasure, not a curse. We learn FROM OTHERS in order to grow up with wisdom and understanding, a Biblical premise.