Everyone is talking about DNA/RNA vaccines. Can they alter our own genetic codes?The vaccine lobby says “Never!” I, however — laboring beneath the weight of a Ph.D. in virology — would instead quote Gilbert and Sullivan: “Well, hardly ever.”Most people don’t know very much about DNA or RNA, so I’ll start with a 30-second chemistry discussion. DNA and RNA are both polymers, long strings (in this case, very long strings) composed of seemingly endless repetitions of a single basic chemical building block, called a nucleotide.The resulting structure is often likened to a string of pearls, or to the rungs of...