I’ve never bought a lottery ticket, and I once spent an entire week in Las Vegas without so much as pulling the lever of a slot machine. But maybe I should have given it a go, because I’ve been lucky since birth—make that since before birth. That’s because before I was anything, I was a twin. Sometimes I marvel at the numbers involved: Only 0.3 percent of pregnancies result in identical twins. I often think about how being a twin is one of the few amazing things you can literally just be born with. Some people are born with a natural talent for music, or a genius-level affinity for math, or supernatural good looks. I’d argue that being born with your best friend is even better—but then again, I’m biased.

When I tell people I have a twin sister, their first question is usually “Are you identical?” and the second is “Do you like it?” I don’t really know how to answer that, because I don’t know what it’s like to not have a twin. (Do you like having a head?) I usually give some clever, vaguely sarcastic response, like “Of course I like being a twin—I have two closets!” What I don’t say is that Liz completes me. She’s my other half. I know those phrases are typically reserved for couples, but Liz and I honestly deserve it more: We’re literally halves; split from the same egg. In Vogue’s coverage of Twins Days last summer, I was struck by something a woman named Joan said about her sister, Jean. “What I always wonder about: The one egg, one sperm, one zygote before it split, there might have been a consciousness. When did it become two consciousnesses? That may be what identical twins experience: the oneness that used to be, before it became twoness.” Jean said, “Maybe that’s why we feel more whole together than when we’re separated.”

Trippy, right? I’m a twin, and even I think it’s trippy. Liz and I aren’t telepathic (another question we get), but we are on the same wavelength. We can communicate a joke with a single look; we’ve had the same wacky dream on the same night in different cities. We’re also each other’s mirror image, so when a friend sees my reflection in the bathroom, she thinks I’m Liz. But being a twin means your life is full of paradoxes and contradictions. Joan said it first—they went from oneness to twoness. They feel more “whole” when they’re together, but they’re two different people. It’s a mind-bending riddle. Having an identical twin sister is at once the most unique, unusual thing about you and the least. There’s another person whose DNA matches yours and whose face is shockingly similar? That’s actually the opposite of unique: It’s repetition.

That was the biggest paradox for Liz and me growing up: We wanted to become our own people, but we were also incredibly close. Conventional wisdom suggests that the only way to become truly “different people” would have been to spend less time together, but that never would have worked. We couldn’t help being best friends. It wasn’t until high school that we started to notice the implications of what that really meant. We were overjoyed to leave our Catholic grade school (and uniforms!) behind for our freewheeling liberal Jesuit prep school (no dress code!): It was my chance to become the girl I really felt I was, to make lifelong friends and no longer feel like I was just “one of the Farra twins.” That turned out to be a little bit harder when a good portion of my new classmates couldn’t distinguish my face from Liz’s. We shared a niggling fear that beyond our group of close friends, no one really cared to know us individually. On our 16th birthday, when it was customary for the students reading morning announcements to give clever birthday wishes like “Happy birthday to Jenny ‘I Beat the School Mile Record’ Smith!”, we not only got a joint wish, but a shockingly unoriginal one: “Happy birthday to Emily and Liz ‘We Look Exactly Alike’ Farra!” (I inadvertently think of this every time a friend sends us each our own birthday card or wedding invite, even though Liz and I live in the same apartment and stare at the same magnet-covered fridge. They don’t even do it on purpose, but I find it endlessly thoughtful.)