The following was published in 1937 Germany. It was intended for teachers & urges them to incorperate anti-semitism into every part of the cirriclum, Reading it now i think it makes a very clear & easy to understand reasoning for parents to teach their children why they shouldnt race mix in later life.
Each kind sticks with its own, and seeks a leader of the same species. That is the way of nature. The time has to come when a boy or a girl stands up and says: "If that is the way it is in nature, it has to be the same with people. To older students, one can explain that a male starling mates only with a female starling. They build a nest, lay eggs, care for the chicks. Young starlings come from that nest. Like is drawn to like, and produces its own kind. That is the way nature is! Only where humanity intervenes do artificial cross-breeds result, the mixed race, the bastard. People cross a horse and a donkey to produce a mule. The mule is an example of a bastard. Nature does not want it to reproduce. It denies the mule offspring. Only man sets himself over the will of nature. He approves and even demands the mixture of blacks or Orientals with white people, or Jews with non-Jews. Each valued member of a race is racially conscious. No White who is aware of and proud of his race will mate with a Negress or a Jewess; even a racially conscious Negro will not mate with a White. Each prefers its own kind. Only an inferior member of a race inclines toward those of other races, or allows himself to be misused by them. Only inferior members of various races mix with each other, the bad mixes with the bad. It is thus clear that the bastard always gets the worst of it, that is, he unites only the bad characteristics of the races he comes from.