I think jewish people and gentiles are two different species of humanoids. So, it isn't an issue of race, it's a issue of relations with a different intelligent species. Mixing genes with other species is dangerous. Not necessarily good or bad, but it's like cloning - you have to be careful about it.

This is why jewish people and gentiles alike have their detractors against 'race-mixing'. They are true to their natures. What if people all of a sudden started to try to breed with monkeys? Hey, they look similar to humans.

So, I think its a genetic war that is going on and the two species are trying to keep their species distinct. Naturally, some characteristics of each species are attractive to the opposite, so you will have crossbreeding going on.

Between the two, desire for certain characteristics arise from one of the species and so one of the species becomes dominant. Well, this ends up as one side always complaining that the other is 'racist' as their qualities aren't desirable. Well, both species are intelligent, so this interrelation between species results in a genetic war can go on forever - with the less-dominant species always trying to weaken and interbreed with the dominant species; and the dominant species trying to keep their species pure and something to be desired.