Once I heard that it was the opposite. The one who comes out first is the younger and the one who comes out next is the older.
I have also heard that before, but I don't buy it. How can that be?
Someone, I don't remember who now, told me this before, too. I was laughing so hard, and I asked her how she could believe it. Twin births aren't any different than regular births if you think about it. Instead of one sibling is born several years after another, this twin is born several seconds after the other twin. How could someone comes later is the older one? I just don't get it.