sNOVA: If I give you a sarcastic remark like " tum to doodh peetay buchay ho, tum nahee sumjho gay ... " does it literally makes you an infant?
Did you read the preceding verses? What is bothering you to be exact? Is it the fact that Jesus(as) spoke when he was a baby? Well its a miracle! like his miraculous birth! why are you overlooking this fact? Other than that i dont find any inclination in the Koran which in anyway suggests that Jesus was a grown up man or a teenager. If you think that is impossible then ask yourself this obvious question : Can a child be born without a father? Its plain common sense