Individuation of women.
The period between 30 and 40 years of age is probably the normal time developmentally for women to complete the individuation from their mothers. Because of the change of object from the primary object (mother) to the secondary object (father), as well as the lack of a narcissistic triumph over the mother comparable to that of a boy's penis, a woman's psychosexual development is more difficult and prolonged. The girl must resolve her attachment to the omnipotent mother and work through her Oedipus complex by deidealizing the father, recognizing that her anal-sadistic impulses do not castrate men, before she can completely individuate. Only then does she become an autonomous, complete woman. Passive-dependency in women is not a mature adult state, as several authors hold, but a partially resolved individuation from the mother, now transferred onto men. Becoming attached to men, idealizing them, they devalue themselves in order not to regress to the omnipotent preoedipal mother. Adulthood (30-40 years) is the time when this resolution can occur because there have been sufficient narcissistic achievements for the woman, enough distance from the actual preoedipal mother, and an opportunity to observe that their own anal-sadistic impulses toward men have not castrated or destroyed them, as well as an opportunity to see men as fallible and human. This is a reason so many woman return to school and begin careers in their 30s. This incomplete resolution is also a reason for fewer original discoveries and creative contributions by women than by men during the course of history. As society changes, this special difficulty for women to individuate may change as well, but I would predict that such change would not be as much as one might expect because of the unique psychosexual development of women.