I meet C at the airport after not seeing her for months. We are both wearing red pants, the same striped shirt, and nearly identical brown sandals. D and I speak on the phone: Where are you? In line for my latte. I’m in line at the post office. E forwards me a poem she likes. I have read it the night before. C, D, and E are my telepathic colleagues. In other words: my sisters.

If you have sisters—and I have three—you will begin, against your better nature, to believe in telepathic communication. It is not unusual to be on the phone—chopping Brussels sprouts—with a sister in Boston, also chopping Brussels sprouts. Over a lifetime your stories of synchronicity and coincidence pile up. But what is actually happening is an overlapping of souls.

Peoples’ characters develop in proximity to their siblings. (I have brothers as well, but for the purposes of this piece I’m speaking of the gals. My brother calls us the Varsity; the three of them, born in a similar row, the J.V.) Who would I be without my sisters? Someone else entirely. No doubt I would be less accident-prone if I didn’t have C as an older sister. She was practical and cautious (read “worried”): It’s going to break, Susan! You’re going too high! And the fact that she was monitoring the world of safety somehow allowed me to take risks. Still, it didn’t keep her from relating. In fact, quite the contrary.

August. Maine. We dock the boat after a picnic. I am six. It is low tide and the long ramp leading up from the float is nearly vertical. I have to lean forward, and when I finally make it to the top I find a wide gap where the railing has pulled away from the pier. Naturally, I lean into the danger of the water, 12 feet below, mesmerized, and fall through the space, landing in a splash. My mother, still on the float and pregnant, as she was for most of my childhood (five children already), leaps in and drags me by the life jacket. C witnesses the plunge and, not waiting to see the result, dashes back to our house nearby, changes into her pajamas (identical no doubt to ones that D and I had), and, shaken, puts herself to bed.

In the company of my sisters, I lose my keys, forget my wallet at the restaurant, leave my ticket on the counter. I am infantilized back to early youth, when someone else, i.e., Mum, was tending to our carefree oblivion. Our minds simply relax to the point where usual personal agency vanishes. We don’t remember where we parked, neglect to turn off the oven.

When siblings share a trauma—one could argue that childhood itself is a trauma—they will be either bound closer together or driven further apart. Our mother died at 48 in a car accident, leaving behind her husband and seven children between the ages of 7 and 21. We were all in shock, moving together like stunned zombies. But it was in a group that we moved, and in a group that we huddled on the life raft together.

Though you come from the same place, it doesn’t necessarily mean you’ll get along, or relate to one another. But if you do relate, your relationship might be among the closest that a human can have. My sisters and I do share many things: political beliefs, a worship of the temple of the movie theater, a facility with watercolors. We have the same voice and the same feet. We all have a compulsion to keep our hands busy—generally involving scissors, glue, string, thread, needles, Scotch tape—in a sort of mania which others might find obsessive, if not eccentric. Now, as we’ve gotten older, we are all planting flowers, preoccupied with our children, and interested in medical matters. My sisters and I are the opposite of squeamish. Stitches, purple bruises, swollen ankles—all are immediately shared, the more details the better. With 11 children between us, there is plenty of material. I spent the day in the E.R., one writes. It sounds, texts E, like the beginning of a poem …

In the cobbling together of becoming ourselves we have been more attentive to our differences—I am the only one who prefers cats to dogs, D is the best dancer—but we always loop back to that dimension only we inhabit. Lately, a seasoned constancy has been established. We can still punch into one another’s feelings as no one else, but we are more likely to bounce back. We’ve had a long time to practice. It helps when you can read one another’s minds.