It’s important to remember that girls and boys don’t have to look different from each other.

In most species of deer, only the male grows antlers, but among reindeer both sexes sport these bony structures on their heads. Starting in middle or late spring, all reindeer grow the new year’s set of antlers, but males lose theirs by the end of November. Meanwhile, females retain their antlers for an additional seven months, meaning that the famous red-nosed reindeer cannot be male.

In fact, sometimes boys and girls are girls and boys.