When my daughter turned 18, it reminded me of something simple but easy to forget: big birthdays are automatic milestones. They come with balloons, dinners, photos, and all the “you’re grown now, woohoo” speeches. There are umpteen scripts for turning 13 through 25 — the OG markers of independence, responsibility, and new beginnings. But guess what: milestones don’t just belong to the kiddos. Sure, we still celebrate those over 30 birthdays with or without parties with 40-deep friends, or sheet cakes full of candles; but it’s a combo of ‘yeah, you’ve made it another year and we love you’ — yet, unless we actively choose it, we don’t tie it…