one of the children i pick-up from school has started to ride to school on his bike. when i pick him up we walk/cycle home. on wed he had his bike with him and i asked him if he had a helmet. he said no and said he doesnt wear one. now should i ask his mum to get a helmet for him? would i be responsible if he fell and hurt his head? i wont let my ds ride his bike without a helmet. obviously his mum is ok with him not having one.