`` it 's all right there in the dna : preternaturality is typically marked by a triple , rather than double , helix structure ; the presence of base pairs that themselves appear to have distinctly unnatural properties ; and the secretion of amino acids-or , as they are more commonly called , preter-proteins-that defy our most basic natural laws , and in doing so , caused a resurgent interest in the pseudoscience of alchemy for a large part of the twentieth century . ''