It's not just you. Just you and me maybe. And it is usually rooted in the relationships adults have with each other.
We are taught that it is OK to use and abuse people as long as we get what we want. And if we leave lasting emotional scars so what? They should have been as cynical, manipulative and jaded as we are. Being loving, trusting or giving just means you're a sap.
It's a power thing. And, of course it is easy to do to kids and in the process turn out another generation of people who are just as unkind to others as you were to them.