Nature vs. Nurture?

While discussing “The Business of Being Born” in class today, we addressed the part of the film that discusses the surge of oxytocin released during natural birth, and how it serves to create a bond between mother and child. This is true for all mammals, yet many can attest to having a very strong bond with their mother, whether they were born vaginally, via cesarian section, or adopted. For me, this raises yet another “nature vs. nurture” debate. My mother gave birth to my younger brother just fifteen months after I was born and thus had two babies on her hands. Because my brother needed closer care as he was an infant, I spent a lot of time being cared for by my father. This apparently had quite an impact – according to my parents, when I was around four or five years old I insisted that I had come from my father’s belly (i.e. my father had given birth to me). While this is a silly misunderstanding by a little kid, I think that today it is quite an apt metaphor because my father and I have an extremely strong connection; we seem to be very much on the same wavelength. Everyone has unique experiences with their mothers and fathers, and of course there is a lot of research that has (and has not) been done on parent/child bonds. But I was wondering what you all lean towards – is this bond (in the case of humans) shaped more by nature or by nurture?