Robert F. Kennedy Jr. has spread many detestable theories in his life, but none is more detestable than his scaremongering over autism and vaccines. It’s not merely that the new Health and Human Services secretary has convinced thousands of Americans that they’re partially responsible for their children’s autism — a trend he once compared to a “holocaust.” It’s that he’s ensuring thousands more will put their children in needless danger for absolutely no scientific or rational reason. One of Kennedy’s claims is the lie that Americans have seen a huge spike in autism cases over the past 40 years. Autism...