A National Geographic special probing the alleged role of Dr. Josef Mengele, ex-Nazi, in the birth of numerous sets of blond twins has come up with no link stronger than folklore. While one Brazilian town of 7,000 does have an anomalously high rate of twins (the blond part is not so surprising, since many Germans fled there), wild claims of Nazi experiments can now be dismissed.
COMMENT: Mengele had nothing to do with this for the same reason he had nothing to do with the fake aliens of Area 51 alleged in a recent book. Not only was the science required a generation (at least) ahead of his time, but he had no idea how to do science. His barbaric tortures were on the most primitive level (injecting dye into the eye to see if they changed color, for example). So we're down to environmental contaminants (possible) or the effects of one or two families with genes predisposing them to a high twin rate becoming established in the lightly-populated region around Cândido Godói and having a disproportionate influence on future births. We don't even know that Mengele was ever there, although some witness recollections indicate he may have visited.