All I know is that they seem to concentrate on one thing at a time it could be walking it could be talking ! Boys tend to go with the walking/climbing girls tend to go with the talking not always though, there are no hard and fast rules.

My brother was two before he said his first word or even tried to walk (mum was pleased as she had twin girls 18 months later and made her life easier) he is now six foot five and worth millions ! I wouldnt worry too much about it he will do it when he is ready.