Baby kissing may be a campaign trail cliche—and a germaphobe’s nightmare—but it’s also a time-honored American political tradition. According to George W. Bush Presidential Library and Museum Director Alan Lowe, who researched the subject for the institution’s new “Path to the Presidency” exhibit, the earliest recorded instance of a politician puckering up dates to 1833 when President Andrew Jackson toured New Jersey. As Jackson stopped to greet a mother and baby, the woman thrust her little boy into his arms. “Ah! There is a fine specimen of American childhood!” declared the president, who then passed the dirty-faced infant over to Secretary of War John Eaton for him to kiss.

While “Old Hickory” outsourced the job, his successor, Martin Van Buren, reportedly kissed quite a few babies, and the tradition took off. Not all politicians, however, embraced baby-smooching. President Grover Cleveland, perhaps not wanting to remind voters of reports that he had sired an illegitimate child, flatly refused. In 1968, Richard Nixon declared, “I won’t wear a silly hat, or kiss a lady or a baby.” He told Life Magazine that he feared such “stunting” would make him “look like a jerk.”

Lowe says that candidates engage in baby kissing because it can help them connect with voters. “The campaign trail can be a rough-and-tumble place, and this shows a softer, gentler side of candidates,” he says. “Voters want to elect someone who is a decent person, and this makes them more relatable.”

That means engaging in an activity that’s not the most hygienic. “As a mother,” said 1984 vice presidential candidate Geraldine Ferraro, “my instinctive reaction is how do you give your baby to someone who’s a total stranger to kiss, especially with so many colds going around?” Ferraro may not have understood the strange campaign ritual, but she kissed the babies nonetheless.