Twins 101: How to tell identical twins apart from fraternal twins

Periodically I like to reflect on life as a twin (as I'm sure all non-twins do constantly, right?), and in order to avoid repeating myself, I sometimes write stuff down. This is the first part in a series of reflections. (I was inspired to post it today by a classmate who is having twins. I thought I would do my own very small part to help her with that.)

It seems like the one thing people know about twins, if there is just one thing they know, is that we can be identical or fraternal. But a lot of people don't know how to tell the difference, or even if it is a good idea to ask. This handy guide should help you out.

How to tell identical twins apart from fraternal twins
The majority of twins—by quite a large margin—are fraternal. So if you just assume that twins are fraternal unless you are told otherwise, you will usually be right.

If one is a boy and the other is a girl, they’re fraternal. Every. Single. Time. Don’t ask. It’s embarrassing.

If both twins are girls or both are boys, it’s a little more complicated. You might have to ask. It’s okay. We don’t usually mind.


Next: How to actually understand the difference between identical twins and fraternal twins. (That'll be a much longer entry, obviously. When I have actual time for that. It's already written but it needs adorable little pictures or something.)