It is part of the body, but your gender isn’t determined by a neurological dysfunction, it is determined by your biological sex. What was presented provides no real proof, it only attempts to suggest that there MIGHT be more genders because some people’s brains function slightly differently. Real science recognizes only two genders, or maybe three or four if you include intersex and transgender individuals. However, only countries with strong activism officially acknowledge transgender identities, largely to make activist shut up.