Cultural influence does not preclude your psychological external locus of control, which is a personal choice regardless of your temperament and culture. Having an internal locus of control isn't the same as not being able to distinguish between that which cannot and that which can be changed, which you kind of imply. Healthy and functional people who have an internal locus of control are generally aware of what can and cannot be changed, accept what cannot be changed, and focus on what can be changed relative to their inherent and chosen values. An external locus of control on the other hand precludes a person from being able to perceive the difference between what can and cannot be changed and shifts the blame for their undesired life circumstances outside themselves. As Stephen R. Covey wrote, "When you think the problem is out there, that thought is the problem." When you learn to love reality, you find the power to make your choices regardless of circumstances.