Jesus (as) will be recognisable by the attributes mentioned in the Qur'an. However, there will be other factors disclosing his identity. No doubt, one of them will be the fact that he will have no relatives, family or acquaintances on earth. Indeed, no one will know him when he comes to earth for the second time. Not a single person will come out and say "I have known him for a long time, I saw him when…" simply because the people who knew him lived and died 2,000 years ago. Thus, no one will have witnessed his birth, childhood, youth or adulthood. Nobody will know a single word about him.