Are these twins "Identical Twins" or "Fraternal Twins"?
I would guess (after googling fraternal twin to mean "non-identical") that they were identical, but I don't know for sure. I myself could tell them apart after a year maybe. And then around age 11 or 12 one got a cheek cut (snowshoveling mishap) that pretty much ended the identical part.
Other facts of the case - I can't remember the mother or father treating them any differently. And after high school I lost touch with them - it would be intersting to see what happened, though.