Identical Twins FAQ

The Most Frequently Asked Questions about Identical Twins

Twin Moms – and Moms of Multiples – face an unbelievable amount of questions whenever they venture out in public. Twins – and multiples – have long held our society’s interest. These are the answers to some of the most commonly asked questions that we’ve heard (and have answers to!) here.

We also have a page dedicated to Facts about Identical Twins, Facts about Fraternal Twins, and Questions Every Twin Mom Dreads (with some great responses from Moms and Dads who have been there!). If you have a question that you don’t see in one of our articles, please contact us. We’ve more than likely heard the question before (in fact, we’ll send a free t-shirt to anyone who comes up with an ORIGINAL question about twins that we haven’t heard before!) but just haven’t had time to write it down yet.

What is the difference between identical and fraternal twins?


Why are some twins identical and some fraternal?

Identical Twins are developed, or formed, when one of Mom’s fertilized eggs splits into two, and each of the halves develop into a separate baby. The split happens within the first 12 days after the egg has been fertilized. If one of the halves splits again, you have identical triplets. If both halves split, you have identical quadruplets.

Fraternal Twins are two separate eggs that are fertilized and then grow into two babies. Fraternal Twins are the most common type of twinning, and the most common type of triplet, quad, quint – and so forth.

Do Identical Twins have the same Emotions?

The fact that identical twins are two different people surprises a lot of people. There is a general assumption that because identical twins share the same DNA, they are carbon copies of each other. Trust me, there is no such thing as identical. Identical twins share the same DNA – it’s not identical DNA, by the way - but once the egg splits, each twin develops on their own. Identical twins develop their own personalities, character, likes and dislikes, hobbies, and emotions just as any other siblings do. They may share some very similar traits, but each twin is their own individual person. It’s fun to watch our own boys as they grow and develop. One likes broccoli, the other prefers green beans. And if you give them cheese and crackers – one will eat the cheese, the other the crackers.

Do identical twins have identical fingerprints?

No. While identical twins share the same DNA, no two sets of fingerprints are exactly alike – including twins. In fact, some mirror twins (identical twins with mirrored characteristics) have fingerprints where the swirls run in opposite directions from their twins’ fingerprints.

Do identical twins have the same IQ?

I actually had someone ask me if our boys SHARED an IQ. I still don’t know what that person meant. Our boys prove the theory that two heads are better than one almost every day (our boys are experts at figuring out how to get to places or do things that they shouldn’t be by working together), but identical twins’ IQ can be as similar or as different as any other sibling’s.

At what weeks are identical twins usually born?

Multiple pregnancies have a shorter gestation period than singleton pregnancies. The reasons vary (twin pregnancies are high risk pregnancies and are susceptible to more complications than singletons, often leading to early or premature births). The average gestation period for twins is 36 weeks, but it is not uncommon for twins to be born as early as 28 weeks, or as late as 40 weeks. (Our boys were born one day shy of 36 weeks and I could not IMAGINE going 40 weeks!) Twins are considered full-term at 38 weeks, and are generally considered ‘early’ if born prior to 35 weeks. Most doctors won’t let a twin pregnancy go beyond 38 weeks because of complications that may occur. Like other babies, twins born prior to 35 weeks may spend time in the NICU to finish necessary development.

Can identical twins be of different sex?


Can a boy and a girl be identical twins?

For all intents and general purposes, the answer is: no. Many people will think boy/girl twins are identical because they look so similar.

Not to create a riot amongst parents of identical twins, but the factual answer is: yes. There are a small number of cases (5 or 6 that have been reported) of identical twins of the opposite sex. To find out more information about how this happens, check out our article on Identical Twins. It is so rare, and one of the twins has severe medical problems, that there is no way this could happen without you KNOWING that your boy/girl twins are identical.

Do identical twins share the same placenta?

Some do, some don’t – it depends on when the egg splits to form the identical twins. If the egg splits within the first few days, they will have two separate placentas. If they egg splits after the first week, identical twins may share one placenta.

What about communications between identical twins?

Do they have a secret language?

Absolutely. There is one theory that says that twin language is developed because of mispronunciation of words between twins. Having twins in our house, and LISTENING to them, I call that theory bunk. I am among those parents who side with the experts – including twins themselves – that say a secret language is developed between twins, and it’s more than just mispronunciation of words.

How are identical twins born?

Approximately two-thirds of twin births in the United States are done by cesarean, and one-third are done vaginally. This is almost the opposite for singleton births. The statistics include those births where one twin is born vaginally, but his or her twin is born by cesarean. It is not uncommon for the second twin to decide to stretch out and enjoy all that room once his or her twin has left, making a vaginal birth impossible. Health complications of both the mother and second twin may also arise after the birth of the first twin to make a caesarean necessary.