Prince Charles and Duchess Camilla, who met more than 30 years before they finally tied the knot, have become the poster couple for passionate rekindled romances. Now Quartz is reporting on a handful of possible explanations as to why such a flame can burn brighter years later.

In the '90s, Dr. Nancy Kalish of California State University in Sacramento studied 1,001 people who'd rekindled an old romance and found that 72% were still with their "lost love"; 71% called it the most intense romance they'd ever had, and 61% said things got hot faster than they had in any other relationship.

Kalish told Cosmopolitan earlier this year that the top reason teens call it quits is due to parental disapproval, and of the people she studied, all but 18% were adolescents during the initial romance, reports the Sydney Morning Herald.

But clinical psychologist Dr. Joe Carver cautions that "suddenly you feel 17 again—and in love," when really, "you actually have no knowledge or understanding of this individual in 2015." And as for 2015, or, at least, this social-media-infused century: In 2004-2005, Kalish redid her study with 1,300 new participants.

In her prior study, 30% of the people involved were married (and therefore carrying on an affair); this time, 62% were married and cheating to be with their lost love.

From Kalish's website: "Because of the high extramarital rate, successful reunions for this group was low: only 5% of the lost love couples married each other; one or both of the affair partners chose to remain married." Would your rekindled love work? In the Washington Post, Kalish writes that "successful rekindlers" are those who first dated when they were 22 or younger, grew up in the same place, were together at least a year, and were torn apart by "situational factors," like a move or parental disapproval.

(Speaking of those who are long lost, these siblings may have finally found their big brother.)

This article originally appeared on Newser: How Reuniting With Your Lost Love Can Work

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