I believe all humans have a kind heart. However, other factors in life may challenge each individual's kindness.
I believe kindness is something we people need to be taught. It is not given to us naturally as we are are not fully aware of our words. The saying "Think before you do something" comes to mind, and in this case its think before you say something because you don't know how much your words can affect a person whether its a negative or positive experience. All though talking is not the main idea of kindness it is part of what makes us kind, our words and how we express ourselves to that person. Another way of kindness is through our actions, but I'll let other people answer this question plus Im talking too much.