User blog comment:VeryUnknownFan/Jayden-G's review of Twinning Isn't Everything/@comment-28381748-20140709070947/@comment-27329394-20140710041130

Not to mention it is entirely possible for a pair of twins to even be different genders.

But yeah, what Ellafan said. There are two twins who look almost the same bar like one feature on my track team and, 2 years later, I still don't know which is which because I haven't really bothered trying to remember. We may notice the mole because we pretty much stalk the show but in real life (or in the show's universe, for that matter), it is a lot harder to notice a difference that minor.