According to Osho, your true identity is the soul—untouched by brain chemistry—while the brain/mind are instruments that express and magnify your tendencies and desires. Desires steer the soul’s journey and roles (plumber or genius), shaping experience without changing essence; alcohol, LSD, or even a transplanted brain only alter the display, not the one who desires.
Who you really are doesn’t change; your brain just makes your wants louder, and those wants choose your path.