My DS2 is 15 months old and hardly tries to say anything. He has said mama a few times if I say it to him but doesn't use it to get my attention - he just shouts or tries to come and get me. He also cannot 'pass me the ball' or whatever - he doesn't take any notice and is quite self sufficient at times and always on the go, completely unlike my first son was. My first son was a real mummies boy, constant attention craving and talking by now - or certainly using lots of nouns and names. They are so different that I am getting a bit worried - should I be?