Homosexuality, especially transgenderism, appears in less than 1% of the population,

LGBT-ness overall has prevalence about 4-5% in population. And most countries on earth don't even have 1% prevalence of intermarriage. Most countries are vastly homogeneous and if there are different ethnic groups they tend to be very genetically similar to each other. That's another thing, nobody would bother to pass intermarriage laws between Croats and Slovenes in Yugoslavia because it doesn't elicit such a disgust as mixing between blacks and whites.