3. You Tell Lies
People lie all the time, and yet most people would claim to hate dishonesty. The thing is that our brains just seem to be wired up for a good fib. A lot of the things you'll say to other people will be, at best, half truths. Some of this is because we're always desperately trying to match our idealised selves with the tragic, disappointing reality. This is because you're privy to your weirdest, stupidest thoughts, feelings and opinions and that sneaky "assumed similarity bias makes you think that other people probably think the same, therefore you try to make up the difference by slightly glossing over the truth. It's also thought that lying could well have developed along with our more advanced social skills. Lying, it turns out, is actually a really good way of getting people to like you. It can be used to spare someone's feelings, a shared fib can bring people together and a lie can cover up something that would otherwise make the group turn on you. It can also be used for slightly more Machiavellian purposes, as a good liar can work their way up the social ladder which, more often than not, leads to success with the opposite sex. This evolutionary favour of the lying types will have caused it to propagate through the species, resulting in you telling that pretty girl that you play the guitar when you definitely don't.