Once more, I googled & pubmedded, but came up blank. The only article on interracial relations and the personality factor Openness is this article. A caveat: some of the questions used to determine your score on Openness are things like "I like to visit art museums" and "I appreciate poetry," etc. One of Eysenck's criticisms of this Big Five factor was that it seems to measure an aspect of intelligence rather than personality. Those who go to art museums and read poetry likely have higher-than-average crystallized intelligence: the facts, etc. you acquire in the course of exercising your big brain in intellectual / academic domains. But assume we refined Openness to only include things like novelty-seeking and noncomformity (some of the smaller traits that make up Eysenck's Psychoticism factor).
Even lacking data I would guess that individuals involved in interracial marriages would score higher on Openness than those in endogamous marriages, ceteris paribus. Still, there is an asymmetry in who dates who, as both Steve Sailer and Peter Frost have pointed out in article form and book form, respectively. In short, women generally prefer somewhat darker men, and men prefer lighter women. So, I would guess that the individuals involved in a dark woman / light man marriage (unconventional pattern) would score higher on Openness than those in a light woman / dark man marriage (conventional pattern). And given that personality traits are moderately heritable, the same would hold on average of their children.
No huge scientific issue at stake here -- just wondering out loud. But there'd be a practical application if true: if finding a mate who scores high on Openness is a big deal, you could locate those of mixed backgrounds, especially of the unconventional dark woman / light man type. Or let's assume, just hypothetically, that you've got a thing for more tawny Italian or Jewish girls (NSFW), but you yourself don't respond exceptionally well to tanning. No problem: just find a girl who's Irish-Italian or Jewish-whatever-northern-Euro-group-Jews-marry, and whose mother is the olive-skinned one, suggesting greater Openness on her part & her daughter's. And because inheritance is not blending, it won't be hard to find a genotypically mixed girl who phenotypically looks prototypically Mediterranean. Now of course, pre-screening who you approach doesn't guarantee success, but if you want to swim against the current of skin color preferences, you're better off choosing to conquer a Class II over a Class IV river.
Personal disclaimer: on my father's side, my grandmother is Japanese and grandfather French-American, making my father 1/2 each and me 1/4 each. My father and one of his brothers look half-to-more-than-half East Asian, and both married white women, which seems rare given that it's usually East Asian women who marry white men. Sure enough, me & my two brothers along with our cousins from our Japanese-looking uncle are the more noncomformist / wanderlustful among our first cousins. By contrast, my mother's siblings married other whites; and my father's other siblings (a white-looking uncle and Japanese-looking aunt) are in more conventional East Asian woman / white man marriages.