If your family were from Galicia(which is not Celtic, BTW), your father wouldn't have changed your name because it would sound Portuguese, not Spanish(Let alone Mexican).
And by the way, the Israelites were natives of the region of Caannaan. You know, Cannaan is the region where Israel is situated and those guys were his more direct neighbours. And by the way, there has not been emigration to Israel until.........1948. Actually, all their history has been the other way round, they have emigrated(and have been discriminated against for the very same reason). And, as far as I'm concerned, Mexico is not giving us any problem since,mmmmmmmmmmmmm,1870s. There isn't a large Mexican community in Spain and, Heaven forbids, Spanish and Americans are as related as Chicken and Turkeys, that is, nothing at all. Therefore, your theory of "revenge" fails(if they're trying to take revenge at all, you know, working in horrible conditions).
Even an "inmigration for dummies" guide says that, if you're living closed to a nation, and you're having economical problems, it's logical that you emigrate there first and foremost, but that's not synonymous with INVASION(in the case of Spain, our problem is with Morroccians and Africans, because they're close to us. Nothing more, nothing else). If Aztecs were replaced with mestizo or White people(70% of the population of Mexico,anyway), they would do the same(and suffer the same result, you see). And by the way, your father's analogy would slap back against him. After all, it was the Spanish guys who invaded Mexico. Maybe problems wouldn't have started if America wasn't discovered because they were the original inhabitants of the land. How do you justify it now, when they go to the States?. Canadians, in fact, emigrate almost as much as Mexicans to United States, either temporarilly or for good, only that they're not poor, you see, and that's why they don't provoke so much hostility. If they were, you'd react the same way.
In any case, Will, bear in mind that if your ancestors are really Mexican(Gallegos there are only in NY and San Francisco, as far as I'm concerned), or Cuban or Argentinian, it's irrelant. There are Mexicans in the country since, at least, 6th generations. If your ancestors had found such a hostile attitude, you wouldn't be saying such nonsenses, to begin with, because you'd be speaking Spanish, German, Irish or whatever language your ancestors spoke, in either Galicia, Argentina, Cuba, Mexico, Germany or Ireland.
Either if you're a self-hating Mexican(it would not be the first case. Bear in mind that Grace Kelly's grandmother, who was the closest to American aristocracy you can find, was Mexican and as many as 50% of the white population of New Mexico or Arizona have at least one Mexican ancestor)or you're making the story up, your lack of culture is not helping your cause. In fact, you're confirming the old saying that racists are not particularly well-informed.