An aspect of Resonance that I left unaddressed at the time of publication, but that I've decided to come back to now, while I'm working on several(!) new stories. Potential spoilers for Chapter 4 of Resonance and onwards follow.
So the question has been asked: is Yael's father racist for insinuating that he objects to his daughter dating a non-Jew? Is Yael herself?
The answer, as with most things, is "it's complicated".
(Note that the usual disclaimers apply here with extra force: I'm not Jewish, but have familiarity with the faith; all errors are completely my own. If you want an authoritative answer to this question, ask a rabbi!)
As I comprehend it, the question of Jews only marrying other Jews comes down to a question of whether being Jewish is an ethnicity, a culture, a covenant, or some combination of the three, and the weight or importance each of these is given.
The very concept of "race" is huge, complex, and questionable in and of itself, and I'm not going to be able to address it adequately here. But in brief, someone in a socially dominant culture (say, a white person living in Canada) saying that they would only ever marry someone from what they perceive to be their exclusive racial group ("I would only ever marry a white person") would generally be considered a racist statement.
But with Jews, there's no one "race". There are certainly distinguishing genotypes (Ashkenazi Jews, for example), but there are many "races" in Judaism: there was a recent black Miss Israel, for example. Traditional concepts of race don't tend to sit well with the reality of modern Judaism. There's also the fact that you can convert to Judaism, as Joshua mulls over, whereas you can't convert into another race (at least as most people understand the concept).
Then there's Jewish culture, or heritage. One can identify as being Jewish and have relatively little interaction with tradition, festivals, etc., but still be part of the culture: for example, many Reform Rabbis would argue that you can be both Jewish and an atheist. Therefore, being Jewish can be an identity that a person can relate to, in different ways.
Third, there's Judaism as a covenant, a sacred bond with God. This one ties Judaism to a belief and set of practices, followed to different degrees. Again, this allows for Judaism to be adopted… although rabbis usually take the approach of trying to dissuade conversion.
So (from my perspective), there's several ways one might be perceived as being Jewish: one that you are conceived in (the "racial" part), one that you grow or are adopted into (the cultural part) and one that you believe in (the covenant). "Being Jewish" may be all three, or a combination, depending on who you ask.
Marrying a non-Jew becomes complicated depending on what the parties involved believe "being Jewish" implies. Racial issues can certainly be present in the marriage if the parties believe the first part. And how to raise children becomes an issue with the second and third. But it's not clear which Yael's father believes, and Yael herself appears to think that just the second, and maybe the third, apply for her.
It's interesting to note that outside Israel the number of cross-cultural interfaith marriages can be very high: the last statistic I looked at claimed that some 40% of Jewish marriages in the US were to non-Jews. This has raised concerns for some in the community, as they perceive this trend to be a "dilution" of the race, culture, or faith (again, depending on what they believe "being Jewish" to consist of). I had a friend who's father sat shiva for her - literally acted as if she was dead - after she married a Filipino non-Jew, and wouldn't speak to her for 10 years.
Given their history, Jews have a completely justified fear of being threatened with extinction, so the response by some to anything that they perceive as threatening the continuation of the Jewish people, as they conceive of the term - including marrying outside the faith / culture / race - can be reflexive and passionate. Personally, I wouldn't categorize most of these reactions as racism, but I can certainly see why outsiders might perceive them that way.