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I think what he was trying to do was spit out the common right wing talking point that they use to explain away the fact that citizens of commufascisocialist countries like Sweden continually report experiencing a much better quality of life than we Americans, even though we're "richer", i.e. because they are relatively homogeneous ("pure" in dimbulb-speak), there is less social conflict.
He seriously flubbed the landing on that rhetorical triple-axle. "Pure" genes? Different races="different species"? No racism here - move along now...