I took some photos at a get together at the weekend. I put them on FB and tagged the people in it. One of the tagged people has used one of my pics as their profile pic without so much as a "like" or asking permission on mine. Lots of their friends are now commenting on their picture that it's a "brilliant shot" and their silence (rather than crediting me) is making people think they took it! This hasn't happened to me before (keen amateur photographer). Am I really going to have to water mark all my photos?!