What will give your relationship the BEST chance at success? It’s not date nights or therapy sessions or romantic getaways – it’s simply marrying someone similar to you! That’s the verdict from a huge study of more than 200 couples married a minimum of 40 years. The common wisdom has long been that opposites attract, like the star-crossed lovers Romeo and Juliet. But the reality is that the more “Romeo and Juliet” your relationship is, the more drama you’ll have to deal with. And the harder you’ll have to work to stay together.

Relationship expert Dr. Karl Pillemer from Cornell University conducted the study. He says being alike doesn’t mean you both have to be obsessed with the Yankees, or “Modern Family” or mint ice cream. It all boils down to having similar core values on things like lifestyle, work, money, and children.

Dr. Pillemer explains that the majority of marriage arguments are kicked off by things that seem like trivial issues, but they’re really core value issues. For example, a couple fights because the husband bought a pricey new suit. The suit isn’t the issue. It’s fundamental differences about money. And the constant financial stress can chip away at their marriage over time. Or the suit may represent work – and the wife may feel her husband is more focused on work than family.

And the study of married couples backs this up. It overwhelmingly found that marriages between people with the same backgrounds and views on finance, religion and lifestyle tend to be the most stable and happiest.

But if you and your partner are different – it doesn’t mean you should split. Instead, Dr. Pillemer suggests doing a “values” check. That’s where you and your partner talk about your basic values in areas like money, children, and work. And if there are major differences – discuss how you’ll handle them. That way you’re prepared to face the challenges and come up with solutions.