When you’re the older sibling, you naturally assume you’ll be the one to hit life’s milestones first. First to graduate high school, pick a college, fall in love, get married, have a baby. It’s even more clear that this is the way things will go when the age gap between you and your younger sister is a whopping six years. And because you’re an independent, strong-willed sort, you naturally assume that the way you do things (or at least the lessons you learn when you do the wrong things) will set the standard for that trusting younger sister, and you think her life will probably follow yours, and she’ll be better for it.

For a time, things seem to go according to your plan. She graduates high school, goes to your alma mater for college, enrolls in one of the same programs that you did. But then she realizes she’s on her own and gets to make her own choices, gets to figure out whatever makes her happy. And it’s then that you discover, much to your dismay, that this little sister, this younger person you’ve counted on to look up to you and follow in your footsteps, is as fiercely independent and strong-willed as you are, and she’s looking for a totally different life than you are.

So you adjust. It’s ok when she gets married before you, because you’re totally happy with your decisions, and she’s totally happy with hers, so why bother with jealousy? You come to see her as a grown-up, not just your kid sister, and you trust that she’ll make a life for herself with confidence, even if it looks nothing like your own. You talk almost every day from across the country, and you begin to see her as your peer. You drink wine together when you’re in the same city and get along with each other’s friends. You look forward to an adulthood of sister best-friendship.

And just when everything is changing again, when you’re both swirling through a time of indecision and big moves with everything up in the air, she does the most grown-up thing either of you will ever do. She gets pregnant!! (omg I’m going to be an auntie!!!) and immediately the swirling stops for her, and she is calm and confident and happy. She knows something that you definitely have not yet learned, and it has totally changed her life. Even with months left until she gives birth, even with the big moves and some indecision still looming, she is a Mother, and you are astonished.

She loves that baby, that person you do not yet know, with everything she has. She is grown up now, in a real and unshakable way, and now you feel like the younger sister. Sure, she still calls because she doesn’t know how to post a Craigslist ad or how to confront her landlord, but she is experiencing something vastly bigger than that, something you’re now looking up to her for.

So sister, I know you’re reading this, and I love you! I’m so proud of you and couldn’t be more thrilled to be your baby’s aunt. I cannot wait to see how you continue to change and become more mature, more caring, more wonderful as you develop into the amazing mother your baby will be lucky to have. You’re going ahead of me now, so when it’s my turn (someday in the future), you’ll get to be the one giving all the good advice and bossing me around! I love you.