This statement means that the brain holds the components to make an individual who they are. The brain is a powerful thing. It holds our memories and experiences. It absorbs information, and it is how we observe and learn behaviors. The components in out brain makes us who we are. It takes the brain to generate an individuals personality, and it takes their brains to make life decisions.
Each person has unique experiences and they process experiences in life differently because of beliefs, upbringings, and what their societies deem as normal. Our brains are constantly learning and absorbing even when we are not making the effort to absorb.The human brain is a remarkable machine.