We often believe our personalities are self-authored, but the mirror system in our brains suggests we are actually biological sponges reflecting our surroundings. From the linguistic patterns we adopt to our risk of weight gain, our behavior is largely a product of social imprinting and the role models we choose to follow. Understanding how to navigate this unconscious mimicry—and when to employ counter-mirroring—is the key to taking back control of your own psychological development.