It would seem that we do not like to share at all.
Sharing is just an idea that people have come up with and agreed upon themselves that they like to think everybody else believes. They don't actually believe it though.
Most people think of sharing as something that only happens in childhood, when you let your friend borrow the toy you got for Christmas because he doesn't have one and his birthday isn't until next week anyways so it doesn't matter if he breaks it or loses it; but adults aren't supposed to share anything ever again!
People are too selfish for that.