Zander has taken to walking on his toes in the last few weeks. My sister keeps telling me that it's not good for the muscles in his lower legs as some will be overused & others under used which can cause problems later.

Has anyone heard this? And how can I stop him doing it? When I tell him to walk on his feet (sounds kinda dumb I know!), he smiles and stomps his feet then keeps going. Kind of like "see I can do it" and then he goes back to his toes! Cheeky monster!