Most of these stolen children were entrusted to the care of Catholics loyal to the regime. The aim behind this was to rid an entire people of the "Marxist gene," at least according to the theories of Antonio Vallejo-Nájera, the national psychiatrist of Francoist Spain, that were widespread at the time.
More accurately it should be Marxist meme. But it brings up the question of looking into the correlation between the traits of biological parents and their long-lost children. Via Dispatches From Turtle Island.