People change and adapt when they’re in a relationship—and not usually in ways that make them more unique. Studies suggest that over time, romantic partners can become more similar in subtle ways. Younger couples tend to have similar levels of health the longer they’ve been together, and couples may even develop similar facial features—by employing the same facial muscles out of unintentional mimicry—over time.

The same phenomenon may also happen on the plate. A new study published in the journal Appetite suggests that couples may develop more similar food tastes the longer they’re together.

In the study, researchers from Poland and Germany looked at 100 couples who had been together for anywhere from three months to 45 years. They tested everyone’s smell and taste preferences by asking them to sniff and rate several scents, like rose, eucalyptus, smoked meat and leather. The researchers then spritzed a series of flavors on the everyone’s tongues: sweet, salty, sour, umami and bitter.

The longer a couple had been together, the more likely they were to share the same preferences for smell and taste. Interestingly, how happy they were in their relationship did not affect this trend.

MORE: Smell Dating: Can You Sniff Your Way To True Love?

The study authors can’t say for sure why people tend to like the same tastes the longer they’ve been together, but they have some ideas. Past research has shown that when couples share a home or many meals, they’re more likely to eat similar kinds of foods. “Shared environment and habits, and consequently exposure to similar olfactory and gustatory stimuli, might together shape similar preferences in both partners,” the researchers write.

There may be a biological tie, too. Previous studies have shown that smell may serve an evolutionary purpose—and some experts say that the more similarly two people smell the world, the more likely they are to be compatible.

There are other possible reasons, of course. People may choose to be with a partner who shares their same food preferences from the start. However, available research has so far has applied that trend to personality traits, not taste preferences. More research is needed to fully understand why people’s tastes converge in relationships, especially over time.

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