I know that in aristocratic circles, incest was very common to "keep the blood pure". How was the attitude towards this subject in the "norma"l population? I guess it wasn't that of a common practice, as if then mankind (or at least some parts of it) would have eradicated itself over the centuries. Was there any conflict between their attitude and the things they heard from (or read in) the Bible, where incest seems to be very common?

I hope my question finds at least some interest and is somehow relevant, I just wanted to write it down here before I forgot it again.

Thanks in advance!