Dualism is a theory in philosophy of mind, not in personal identity. It doesn't have any opinion about who "you" are, so it doesn't have any opinion on the coun

Dualism is a theory in philosophy of mind, not in personal identity. It doesn't have any opinion about who "you" are, so it doesn't have any opinion on the counterfactual "But for luck, I could have been less smart." It sounds like what you really mean is something like a psychological continuity (identity is having psychological continuity) or animalist (identity is being the same human animal) view, which are both consistent with some mental characteristics (like intelligence) being accidental to who we are.