I recently celebrated my birthday. Although it wasn’t a milestone year, I still celebrated with cake and flowers with my family — a far cry from the fanfare and festivities I enjoyed, even demanded, as a child, when our birthdays were all-day and sometimes all-week celebrations, with themed parties, favors, special food, and gifts. I didn’t grow up in a wealthy family. Even so, as a kid, birthdays were a big deal — celebrations were a common, expected occurrence. It never would have occurred to me at the time that there are millions of children in the world whose birthdays come and go just like any other day. They don’t have a party. They don’t get gifts. They don’t eat...