i think it has more to do with a kind of mindset than a culture thing .. i know lots of people have problems 'respecting' such cultures which impose restrictions on basic human feelings..So Qlady,asking smbdy to 'respect'something they actually dont amounts to 'imposing' it on them..
missx,generally the 'sin' part of it stems from the reasoning that sex is a bad thing..
i knw bcos i've seen it even back home where many ppl dont look at sex as 'makin love' but as 'dirty'..