What is it about twins that’s so darn fascinating? We idolize them when they’re famous (ahem, Mary Kate and Ashley), we envy them when we’re young (I know I’m not the only one who dreamed of having an identical partner-in-crime as a kid!) — some women even stick to conception-friendly diets said to increase their chances of having adorable little duos.

But no matter why we love ’em, there’s one thing for sure: With a recent report from the U.S Centers for Disease Control and Prevention (CDC) disclosing that more twins are being born in the United States now than ever before (birth rates have soared more than 70 percent in the past 30 years), there’s going to be a lot more pairs to go around!

And with such a surge, there’s no better time to learn more about them. For example, did you know that there’s a “twins gene” — or that two twins can have totally different dads? Brush up on your twosome health trivia here.