IStock Photo 3812622 © Jacob Wackerhausen

“I knew I wanted to marry Kate when I met her,” Tom Cruise told T: The New York Times Style Magazine. “I bought the ring shortly after that first date.” That’s so romantic that only half of us think it’s even possible: The odds an American believes in love at first sight are 1 in 1.92 (51%). Meanwhile, 1 in 2.5 of us have experienced it ourselves.

There’s not much debate surrounding the simpler notion of attraction at first sight. Sight says a lot: An interested man’s eyes will linger for 8.2 seconds on average, compared to the 4.5-second glance he gives a woman he finds less attractive. But only 1 in 4.55 unmarried adults puts physical appearance at the top of the date-worthy qualities list. The real search is for someone who is looking back at you; research confirms that direct eye contact is sexy.

So can you find that “one true love”—in whom 1 in 1.35 (74%) adults believes—just by looking? Probably not; smelling is a better bet. In the famous sweaty t-shirt experiment, women sniffed anonymous men’s dirty clothes and rated their appeal. The women—at least the ones who weren’t on the pill—were more attracted to the odors of presumably genetically-compatible men, those whose immune system genes were different from their own. At least two dating services are now selling romance by way of DNA testing. According to scientificmatch.com, with the right genetic union couples can achieve higher fertility rates, healthier children, less cheating, and more orgasms (on the woman’s part, at least).

Whether an instant connection will last is another question. Only 11% of 493 Israelis surveyed said their long-term relationships began with love at first sight (or scent). Where lifelong love is concerned, we humans could learn a thing or two from the monogamous prairie vole. They cement their pair-bond with sex, which releases the hormones oxytocin in females and vasopressin in males—a fact some hucksters (and some scientists) are trying to leverage toward a modern-day love potion.