The Merchant of Venice: Nature, Nurture, and Conversion

Alright, I originally had four general ideas, but three of them have ended up pretty well merging. That has been the topic of most of my research. Here's what I've got:

I am studying The Merchant of Venice. Obviously I've found a LOT of material on racism, how it is manifest in TMOV, to what degree this can be read as a racial text, to what degree we can call Shakespeare racist, etc. However, while I was reading I found that the racism present in the play really presents a question of nature versus nurture more than anything, and scholars, surprisingly, seem to have very little to say on this topic.
The moments in the play which I think most illustrate this question are when Shylock claims that he has been called dog and a devil and all those things, so now he is acting like one; when Jessica and Lancelot discuss whether or not her Christian conversion will save her from hell; the fact of the absence of Jessica's mother; when Shylock is forced to "convert" to Christianity; the brief but still intriguing mention of Lancelet's unborn child by a black woman; and Portia's evaluation of the different suitors (especially, of course, the black Prince of Morocco).
One option I'm considering is staying mainly within the text and evaluating the question (I really haven't come to any conclusion whether we should read this as an argument for nature, or for nurture, or if it just explores the topic without coming to any kind of conclusion), in which case my thesis would essentially be that while racism and religious prejudice are clearly foregrounded in the play, at the root of their presence is really the question of whether the individual characters are shaped by their blood, or their heritage, or if the circumstances under which they live make them who they are.
I've researched some historical context concerning slaves, Jews, and even animals (Shylock is frequently referred to as a dog or a wolf) which has also contributed to this question of nature versus nurture in  categories that were considered less than human.

Something else I have considered is very similar: the topic of conversion. I don't really have an argument with this one at this point, but we have some interesting examples of "Christians" who were born into the faith and revered for being Christian but really don't act as we might say Christ would. We also have Shylock who is forced to convert to Christianity, and the questions that raises. How can one be forced into conversion? And then, obviously, there is Jessica who marries a Christian and is "converted" in that way. Did she have a personal conversion? Does her Jewish heritage prevent her from being redeemed in the Christian sense? Does marriage to a Christian redeem her? Of course I'm not trying to answer all these questions, but just see what Shakespeare and history have to say about it.