Annie: Well, I didn't address the issue of "corrupting other groups" by marrying them. I don't think William Joyce is making that charge.
He makes the charge that the Jews want all other races to lose their racial consciousness, while the Jews keep theirs.
There is a psychologist in California who has worked this whole idea out in detail ... he calls it a "group evolutionary strategy".
Now, this fellow in California probably would argue that this "strategy" is unconscious ... just something that has evolved, like the instinct of the coo-coo chick to push the original eggs out of the host's nest.
But William Joyce implies -- if I understand him -- that Jews operate as a kind of collective entity. That each Jew -- perhaps with a few exceptions -- thinks of himself as a Jew first, and takes political positions -- say, on things like immigration -- designed to weaken other groups.
I don't think that's true. Jews obviously tend to agree on support for the Jewish state, and form the basis for a powerful lobby group to advance the interests of the Jewish state. But so do Cubans form such a base, so do Armenians, so do many other "hyphenated Americans". It's perfectly natural.
What disproves the "Jewish conspiracy" idea is that Jews are destroying themselves, as a group, by an extremely high out-marriage rate. If you are a Jewish "nationalist" (I cannot find the right word here), you will be very alarmed by this trend. In any case, I think it destroys the "Jewish group consciousness" idea. If there were such a thing, Jews would have a very low out-marriage rate.
Note: there are some technical issues here, for those interested, such as what happens to the non-Jewish partner, and the children of a mixed marriage... how many "become" Jews, etc. Answer: not many. The trend is down, and it is the same in Europe, although, of course, not in Israel.