Well, indeed a million dollar question, but this is not the right moment to seek those details! Control your horses! Remember, this is not a messenger chat, where you can ask anything to a stranger and get away with it. You are sitting in front of a person whose temperament and nature you hardly know. Just like girls, even boys find such questions an attack on their character. Moreover, if he asks you the same question, it might make you uncomfortable as well. But, yes, you must insist on a pre-marital medical check-up after the things are finalised and you are all set to marry him.
Must Read: 4 Signs That He Is Not The Right One For You