That wasn't the question. The answer is, pretty much everyone in every culture thinks it is wrong to assault that person.
Now please provide me a rational reason why it isn't wrong for me to hurt you for no reason if we proceed from the assumption that it is wrong for you to hurt me for no reason. There is none, so it follows that it is just as wrong for me to hurt you as it is for you to hurt me. Voila, the golden rule. It doesn't take a genius or a prophet to figure it out.
The question was specific to particular persons and therefore is irrelevant in a discussion of general morality. It is not true that in "every culture" it is wrong for any person to assault any other person. There are societies in which it is OK and even commendable for some people to assault other people.
Now please provide me a rational reason why it isn't wrong for me to hurt you for no reason if we proceed from the assumption that it is wrong for you to hurt me for no reason.
I claim that you cannot reason from the assumption "that it is wrong for you to hurt me for no reason" to anything. You need at least one other proposition to get to a conclusion. You are making an unstated assumption that you and I are in some way equivalent (a Christian notion).