I think it's most likely that I would have been a muslim, yes.
I think if I were around when Christ was I would have been one of the Jews trying to get him killed.

Yet, I'd like to think that I would see if I could defend and rationalise my faith.
Isn't is obvious that if a person has exposure to beliefs they are more likely to accept it, it's only because they have had exposure to it.
A person who I really respect was brought up in a Jewish home, he now believes in Jesus, against his family's wishes, he has been quite excluded from his family.
I like to think that I would measure the accuracy of my beliefs with personal experience and finding relevant answers to my questions.