By Jonah Berger, author of Contagious

　　In this year’s third-grade classes, teachers might have noticed an unusual number of Kaylas, Katies and Kyles. This follows an earlier bump for Alexes and Amandas, and other names that start with A. Why? One factor might be…the weather.

　　As part of our research on trends and how ideas catch on, my colleagues and I analyzed more than 125 years of data on the popularity of baby names.  We found that names that begin with K increased 9 percent after Hurricane Katrina in 2005. And names that start with A were 7 percent more common after Hurricane Andrew in 1992. It wasn’t that people named their babies after the storms. (In fact, fewer people named their children Katrina and Andrew after each respective hurricane.) Rather, it was similar sounding names that spiked after particular storms. Predicting cultural trends is of great interest to companies, consumers and cultural critics. Will a new song be a hit or a flop? Will turquoise be the new black? Will a particular public policy idea catch on or fizzle fast? There are big stakes — big rewards — in being able to accurately forecast cultural trends.

　　Predicting the future, however, is notoriously hard to do. It’s easy to find examples of things that have caught on. Low-fat Greek yogurt. Tablet computers. Fifty Shades of Grey. But even “experts” have difficulty identifying hits before they take off. J. K. Rowling sent her first Harry Potter book to twelve publishing houses, all of which turned her down. For every “futurist” who predicted the organic food movement, there were ten who predicted that “mechanized hugging booths” would be the wave of the future.

　　The data on first names that I mined with my colleagues, Eric Bradlow, Alex Braunstein and Yao Zhang, suggests an identifiable indicator of future popularity. Conveniently, there’s no shortage of data. Everyone has a first name. And previous research has shown that names affect everything from how attractive people seem to others to how many callbacks they get from future employers.

　　But what explains the appeal of a particular name? A key factor is the association a particular name conjures. Madeline might sound nice if it reminds you of your best friend in high school; Molly would likely be less appealing if you had an evil boss or crazy aunt with that name. Popularity plays a part in name selection too. Some parents want uncommon names (Blue Ivy), but most want something more mainstream. Too popular though, and people may avoid it.

　　Beyond the name itself, we found that the popularity of other similar-sounding names plays a determining role. People are more likely to name their child Madison when lots of Morgans, Michaels or other babies with names that begin with M have been born recently. Or when more Katelyns, Allisons or other young children are born whose names end with an N. Hurricanes have a similar influence because they increase the frequency with which we hear certain names. The more damaging the storm, the more frequently we hear its name.

　　Are people so easily influenced? Apparently. We like what we know or what looks and sounds similar to what we know. Modern art might seem grating the first time we see it, but after you’ve seen a couple of Picassos, Kandinskys are more pleasing to the eye. The same is true for names. Hurricane Sandy brought to mind negative thoughts, but hearing it over and over again could make names that start with an S sound better. Even if we have no idea that the hurricane is what made them sound so appealing.

　　The lure of the familiar has evolutionary benefits. It helps children bond with their caregivers, guides animals toward plants that are safe to eat and helps spouses stick together through mood swings, piles of dirty clothes left on the floor and other annoying things that never seem to go away.

　　Similarity shapes popularity because it makes things feel familiar. Whether a certain song takes off or a new car becomes immensely popular depends not only on the car or song itself but also on how similar they are to others that have been popular recently. Greek yogurt sales have been buoyed by the big success of low-carb, high-protein diets. And Fifty Shades is similar to another blockbuster book of the recent past– the implicitly sexual vampire fantasy Twilight.

　　Jonah Berger is an Assistant Professor at the Wharton School at the University of Pennsylvania and is the author of the New York Times bestseller, Contagious: Why Things Catch On.