We know that Freud defined instincts as originating from pregenital areas. In our opinion, the basic onset mechanism of the pregenital drives is associated with the organism's lack of support for instincts due to neoteny (the production of human offspring in its juvenile form) and heterochronicity (differential growth rate of organs when someone is born). Orga-nism may have an instinct (let's say, repro-duction), but it is not mature enough to satisfy it (hormones are mature, but sexual organs are not mature yet). In this case, one meets the satisfaction of this instinct just like satisfying another instinct his/her organism is capable of. We report a case that manifest aggression only during sexual coitus not in daily life.