This question was recently posed to me, followed quickly by "I know that's a dumb question."
Believe me, I've heard my share of dumb questions, but after answering with, "I don't know if they know they're twins, but they are well aware of one another," the question came back to mind several times in the proceeding days.
I've worried from their very first weeks that some damage was done to their twinship by not bedding them in the same crib or feeding them together. I guess overall, we've treated Trace and Alysse like two singletons that we care for simultaneously rather than like twins.
Books written by experts suggest parents of twins allow them to sleep in the same crib, as they are more comfortable together; and encourage a single feeding schedule to simplify life. This advice didn't seem to best suit Trace and Alysse, and our family as a whole, so we adopted an eat-when-YOU-want-to-eat schedule and separated them not only in their own beds, but separate rooms, when they were only a couple weeks old.
During their first months of life they seemed to exist solo ... completely oblivious to one another. I remember silently agonizing over whether or not we had destroyed some special twin bond between them. Everyone believes there's a special relationship between multiples. Had we taken that from them in our attempts to care for them in the manner we felt best met their needs?
Slowly, as they became more aware of their surroundings, I began to see more interaction between them. Slowly, I began to feel a bit relieved that we hadn't taken from them a special bond they hadn't been given the chance to develop.
Do they know they're twins? Yes, I think they do.
In moments of fussiness when nothing else seems to calm one or the other, placing them together so that they can make eye contact seems to bring a sense of peacefulness and instant smiles. Once this connection has been made, they seem to coo and smile at one another as though they both know something no one else does.
Perhaps more telling is when laying them at opposite ends of a blanket, one way or another they find a way to meet up, and within minutes their hands are joined. Babies holding hands ... it still melts my heart every time I witness it. They seem to have a need between them to touch that I don't know two non-twin infants would share.
I do wonder, though, how this relationship will evolve as they grow. Several times I've been told that in a twin pair there's usually one child who is more dependent upon the other. This twin phenomenon I can't say I've yet seen in our pair. If each can be their own independent person while sharing a relationship not many of us know, I'll be happy knowing we've accomplished something most parents don't have the pleasure of attempting.