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Let's face it - everyone isn't nice. In fact, being nice is more difficult for some people than others. But is it possible that "niceness" is predetermined by our genes?

A new study in the journal Psychological Science suggests this: If you think the world is full of threatening people, you're not going feel compelled to be generous by doing things like volunteering and donating to charity. But if you have certain gene variants, you're more likely to be nice anyway.