Stereotypes don't just appear out of the blue... They are based on some fact, and I'm sure that Italians and Greeks have a lot of stereotypes, but Jews are known for being greedy and materialistic
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stereotypes can also be based on half truths and misinformation... Jews using the blood of Christian babies to make matzah is a perfect example.... of course there's no truth to it, but as you said, stereotypes don't appear out of the blue. for centuries, jews were barred fromalmost all professions and were relegated to money lending, tax collecting, and anything else no respectable Christian would take part in... hence the stereotype.