No two brains have identical histories even when anatomically alike

Evidence

The fact that synapses can see their efficacy reinforced or weakened as a function of experience thus allows us to assert that, even if all human brains resemble each other with respect to their anatomy, no two brains are identical with respect to their history. The phenomena of learning and memory show this directly. Repetition and habit play a considerable role, and this reveals that the response of a nervous circuit is never fixed. Plasticity thus adds the functions of artist and instructor in freedom and autonomy to its role as sculptor. In a certain sense, it is possible to assert that the synapses are the future reserves of the brain. They are not immobilized and do not constitute simple transmitters of nervous information but rather have the power to form or to reform this very information. — Catherine Malabou, What Should We Do with Our Brain?, 91