"Society ingrained that we shouldn’t mix. Our nation is founded on that kind of ideology and it’s still woven into our culture today."
Do we really think it's true that it's only
"our nation" and "our culture" that have ingrained this?
I'm not sure I know of any nation or culture that doesn't.
In which case, it's entirely possible that this kind of response is something that is hardwired into us.
Which actually makes some sense, if you look at things from the perspective of someone living in a tribal unit of 100-150 people whom you have lived among your entire life. There are very strong reasons for not venturing too far away from your own group. The guy from the next village over might be OK. The guy who talks funny from a hundred miles away (that's about a week's worth of travel on foot) will be highly questionable, and for good reason. As distances and differences grow (differences in language, belief, appearance, music, dress, everything), the more and more questionable those choices are going to seem.
And it's also very well documented that the more differences there are between groups of people, the more they tend to "objectify" (to use the term employed by the article) each other, i.e. fail to see each other as individuals. For proof, consider the comments sections on any political posting on the internet (liberal or conservative).
Of course, different people have different levels of tolerance for differences, which is probably what the study is revealing.
But beyond that, when we look at many bi-cultural couples (a far superior term than bi-racial), I wonder how many of them result in one partner assimilating more to the other partner's culture in a very unequal way, rather than simply blending the two. I suspect that that happens a lot. And then the couple really isn't bi-cultural any more, is it?
That also suggests another potential avenue of inquiry: members of cultures who feel themselves to be in a strong position may by more likely to be comfortable with bi-cultural couples because they know, at least on some level, that such a couple is likely to acculturate in their direction. However, if you feel that you are in a weak position culturally speaking, then you are far more to police the boundaries of things like intermarriage, mixing between cultures, etc.
Anyways, lots of opportunities for more research.