When we found out we were having twins, we knew they were identical. We had only put one embryo in. And I panicked. Not about much else, but about this. I was terrified I wouldn’t be able to tell them apart. That I’d mix up their names, their needs, their little selves, in the fog of newborn twin life and beyond. Here’s what nobody told me: identical doesn’t mean identical at birth. Even with the same DNA, twins can look really different in those first weeks and months — birth swelling, position in the womb, blood flow differences if they shared a placenta. Even epigenetics plays a role, where the same genes get expressed differently between them. And in our case, there’s another layer. The twins carry Brit’s DNA, but Sydney carried them. So even their “identical” genetics arrived into two slightly different bodies before they were even born. Three months in, my fear hasn’t come true. I can still tell Benny and Dash apart at a glance. Their features are so distinctly theirs. I do...