"Parent Trap" Redux?

Do you remember the movie The Parent Trap? Not the Lindsey Lohan version, but the older, Hayley Mills version. I adored Hayley Mills as a kid, especially that movie (and Moonspinners, which fewer people know). Twin girls, separated at a very young age by their divorced parents, meet up accidentally at summer camp and conspire to get their parents back together. They switch identities, shenanigans occur, and by the end Maureen O'Hara is swooning for her ex-husband. Great movie! I used to fantasize about being a twin, or having twins when I got older.

Oh my! You look like me!

And here we are. I guess this means it's all my fault, right? Except we were almost positive they're fraternal, because they are what's referred to as "di-di." This means they are dichorionic (separate placentas, or "bubbles" as I like to call them) and diamniotic (separate amniotic sacs). Di-di, get it? Other possibilities are mono-di and mono-mono, which is the riskiest type (60 percent survival rate -- yikes!). Di-di are the lowest risk, which is great news for us.

However, today on a twins online board, I read in someone's post that 20 to 30 percent of di-di twins are identical. That range seemed a bit high, so I did a little research (slow day at work). The actual fact is that 20 to 30 percent of identical twins are di-di. And about 33 percent of all twins are identical, which gives us an actual rate of about 10 identical sets for every 100 di-di twin sets. Roughly.

So it turns out we have a 10 percent chance of having identicals. Crazy!! This only happens when the egg splits within three days of fertilization. But it does happen! I find this both cool and terrifying. Those girls switched on their parents so easily in the movie! I know they say parents always know, but the twin board has led me to believe it's quite otherwise. One woman even had to bring her identical boys to the doctor to have him figure out which was which (they were very young at the time so the boys couldn't tell her).

And the only way we'll know--if they are the same gender--is by a DNA test. Crazy! Of course, if they are boy-girl, we'll know immediately that they are fraternal.

But this could be our future:

Imagine waking up to that in the middle of the night!