You get a C+ for your psychology paper. Just to add to the 'peer review' element of this scientific discourse:
1) It can be argued that in order to learn assertive behaviours, a gender specific role model is required. If there is no father present, then it could be said that NOT HAVING A FATHER would mean a lack of assertive role model. If in addition mother is very domineering, you may end up even more unassertive.
2) You haven't factored in the influence of brothers and sisters and external social influence such as strong role models - vicars, teachers etc (gender specific or otherwise)
3) You haven't factored in single catalysing events or repeated negative events that can lead to social phobia, such as trauma.
Despite what Freud said - it doesn't all come down to your parents and whether you want to get oedipal with your mother. A lot of people now think that Freud was way off the mark with much of what he said. Certainly a lot of his psychotherapeutic techniques and approaches are now thought to be counter productive, and its one of the reasons the newer therapies such as CBT, do not AS A RULE look into childhood experiences as part of the cure. They may be used to define how behavioural patterns formed, but you won;t hear a CBT therapist telling you that you have buried frustrations at your mother. Its worth noting that Freudian psychotherapy in general takes twice as long as CBT to achieve any kind of therapeutic aim.
Freud died at the outbreak of World War II and his theories even then were hugely disputed. Nowadays this is even more true, but his ideas have permeated popular culture so much that we have people all over the place blaming someone else for how they are, rather than look for ways to overcome their difficulties. I hope that the next 20 years will see a dropping of this man's ideas as people learn to empower themelves against their past and make the choices to improve their lives.
I had an absent father and a mother who tried her best. I believe my SA came from 4 years of verbal and physical bullying. I understand the source - it doesn't do ANYTHING to help me overcome symptoms of anxiety or depression.
As for the black thing - I dunno. If its true then maybe there's a cultural element. Us white folk have a habit of being brought up under the residual influence of puritanical religions. I'm not religious, but I am english - and hell, that really adds up to a sense of uptightness, especially around women. SEX. What a filthy word. Ugh
If you think you lack assertiveness, there are many books and courses you can go on.