Twins Development and Language


Facts and figures

Researchers at the Australian Twin Registry at Melbourne University have estimated that in Australia one in 80 births will result in twins, while one in every 6,400 births will produce triplets, and that quadruplets will be the outcome of only one in 512,000 births.

What kind are they?

Identical, or monozygotic (Mz) twins arise from a single egg being fertilised by a single sperm. The twins' genes are identical, and are always the same sex (boy-boy or girl-girl pairs). 

Fraternal, or dizygotic (Dz) twins arise from two different eggs being fertilised by two different sperm, and, like any siblings, have about 25% of their genes in common. Half of all fraternal twins are boy-girl twin pairs, a quarter are boy-boy, and the remaining 25% are girl-girl. 

The fertility of twins falls in the same range as the rest of the population. Women who are themselves fraternal twins have a 10% chance of producing twins, identical twin women have only a 0.6% probability of having a twin birth. 

Once a woman conceives twins, she has a 5% (that's one in twenty) chance of having twins again. There are no interesting parallels to these percentages among dads! A man who is a twin has the same probability of fathering twins as any other man. 


The prospect of having twins can be both thrilling and daunting!  Reading the books and pamphlets that abound (and, for that matter, surfing the net for information) can be both reassuring and worrying as issues that the expectant parents may not have considered before are frequently raised. We know for example, that complications during delivery occur more often in twin births than in singleton births, and that prematurity and low birth weight are more common in twins than in singletons. 

One of the best preparations the expectant mother of twins can make is to ensure that she has adequate rest, nutrition and sensible exercise during pregnancy. This is generally easier for first-time mothers to achieve. If these goals can be accomplished, then the health of both the mother and the babies can be optimised.


Knowing in advance that twins are on the way allows parents to prepare emotionally and practically. There are well established support groups in Australia for multiple birth families linked through the Australian Multiple Births Association (AMBA). Among the services and support offered by AMBA are newsletters, library services, videos, an education program, telephone support, home and hospital visiting, discussion groups, social activities, pram and stroller hire, an equipment exchange and a clothing pool. An important role AMBA fulfils is to provide information and support for bereaved and special needs families.

Those who don't like the idea of participating in a community twins organisation may we wise to develop their own informal network in advance. Plans could include arrangements for both parents to be around as much as possible in the weeks following the twins' homecoming, and arrange for a relative or other helper to assist with housework or with your other children while you are getting established in a routine. 

Baby equipment

Twins can share a certain amount of baby equipment, but it is necessary to have two of certain items ready, for example: two bassinets or cots, two capsules, a twin-stroller (the face-to-face style is often easier to manage), two sets of bedding and clothing, and two high chairs. It is helpful to think about home safety before it is actually necessary and to invest in some child safe locks. As "accomplices" twins can get up to a lot of mischief. If the house and garden are twin proofed the task of keeping an eye on them both is made easier.


Older siblings need to be prepared. It is unwise to suddenly "start" them at day care or preschool as soon as the twins arrive home. Any changes to their routine are best made before the twins are born, or deferred until they have adjusted to the inevitable changes they will bring to the family dynamics. Siblings may need to be reassured that they are special and loved. If they are jealous it may help them if they talk about their feelings.

The early weeks

Twins may attract more visitors than normal to the household, at a time when the new parents may be quite sleep deprived. Research has demonstrated that fatigue is the main trigger for depression in new parents. Of course, maternal depression is good for neither mother nor babies. A National Institute of Child Health and Human Development (NICHD) study of depressed mothers in the USA  showed in part that:

Lower levels of maternal sensitivity in depressed mothers partly explained their children's poorer school readiness, verbal comprehension, and expressive language and higher rates of problem behaviour. This suggests that depression can lead to less sensitive maternal behaviour which, in turn, leads to poorer child development.

It is a good idea to have a strategy in place so that the mother does not wear herself to a standstill providing hospitality to grandparents, friends and neighbours who have come to play with the twins. 

Say yes!

Some parents of twins have a "to do" list posted on the fridge for anyone who volunteers, and others make a firm decision to say "yes" if friends offer practical help. Many new mothers report a sense of being tied to the house and being bogged down in a seemingly endless round of nappies, baths, feeds and household chores. 


Even if her partner shares these tasks the full-time, stay-at-home mother can resent his opportunity to "escape" to work, while fathers can feel marginalised and unappreciated. Regular use of babysitters from an early stage, so that the mother can have a rest, go out on her own, catch up on her interests, or so that the parents can spend time alone, can alleviate these stresses without threatening the bonds between babies and parents. 


Demand feeding, or feeding infants according to their individual patterns, can be lengthy and tiring with twins. An option many parents prefer is a modified demand schedule where the baby who wakes first is fed, and then the other baby is woken up for his or her feed. If both babies are good feeders simultaneous feeding is an option. Mothers often need encouragement and support, as well as adequate rest, to persist and feel confident about with breast-feeding twins.


The intelligence (IQs) of identical twins rarely varies more than five points, while the IQs of fraternal twins may be as different as those for any siblings in a family.

Social development

Identical twins usually have very similar social development. Each is typically about as outgoing and communicative as the other, and they tend to share similar attitudes, feelings and reactions. Fraternal twins, on the other hand, differ from each other as any siblings would.

Closeness and dependency

Girl-girl twin pairs twins, especially identical twins are inclined to be more dependent on each other than boy-girl or boy-boy twins. Identical girl-girl twins are also likely to have an emotional closeness all their lives. In descending order, closeness and dependency are strongest in fraternal girls, then identical boys, then fraternal boys, and finally fraternal boy-girl twin pairs. Identical girls are most likely to remain very close throughout life, followed by fraternal girls, identical boys, fraternal boys and boy/girl pairs.  


Twins' closeness may make them conservative about socialising with others. They may make a communicative little team, but then be very shy when they have to branch out on their own. 

Friendships, individual outings, and individual treats will help to foster individual confidence. Others should be encouraged to call them by name, rather than referring to them both as "the twins" or to either of them as "twinnie". 

Nurturing simple decision-making ("Shall we have pizza or spaghetti?") and making choices ("Which book will you choose?") from an early age helps each twin to become an identity. 

Allowing one twin to be spokesperson for the pair needs to be discouraged. 

As they grow older twins can start to express their individuality by having different clothing and their own special stories, memories and possessions. They should each have their own "space", a place to keep their special treasures, and their own storage (or storage section) for clothes and books. This is particularly important in terms of learning to share. Children cannot share until they understand "ownership". Twins usually learn about sharing and co-operation earlier than singletons, which means they are often popular with other children as play companions. 

"Twin language"

A fascinating part of many twins development is the emergence of idioglossia, or "twin language". Recent research suggests that twin language is most often seen in twins with immature or disordered language, especially when the twins are performing at the same developmental level. 

An interesting Australian study found that twins were less adventurous in their use of words when playing with each other than they were when they played and chatted to adults. They used simple language and fewer words when they talked to each other. A British study showed that twin language is higher (around 50%) in twins with speech and language difficulties than for twins with normal language (11%). 

Speech and language development



Typical speech and language acquisition

Late talking twins

A child is considered to be a "late talker" if they have a spoken vocabulary of less than 50 words at 24 months. This does not mean that the 50 words have to be pronounced perfectly - two year olds are supposed to talk baby talk!

If twins are late to talk it is important not to assume that they will automatically "catch up" in time. it is a wise precaution to take them for "baseline" assessment by a speech pathologist who will monitor their progress at intervals, provide helpful advice and guidance, and suggest therapy if necessary.

Fostering development

A few simple strategies can be employed to help twins' language development. Some of these are easier said than done in busy families, especially if you are sleep deprived!

  1. Make a point of learning to recognise, and seize opportunities, as they occur, to talk to one twin at a time.
  2. As well, actively create opportunities to talk to one twin at a time. For example: a couple of nights a week bath them separately; when the family goes for a walk, one parent take one twin around the block in one direction, and the other parent take the rest of the family around the block in the other direction, and meet up; on family walks, have one parent and a twin leave earlier or later than the rest of family, and meet at the destination.
  3. When you give directions to your twins, give them to each twin individually (not to both at once). Make your directions or instructions simple and specific, using a minimum of words, but remaining grammatical. e.g., "John, put your socks in the basket..." then "Lucy, put your socks in the basket too". 
  4. When a twin follows a direction (does what s/he is asked or told to do) praise him or her individually. Don't let your twins always have to make do with joint praise. e.g., "Thank you John. It's a good help when you put your socks in the basket for Daddy" then "Oh Lucy! That's great. You put your socks in the basket just like I said".
  5. When you are playing with both children, or doing an activity with them, try to have one twin finish their conversation with you. Let each twin have two or three or four conversational "turns" (you speak, child speaks, you speak, child speaks...). Make sure they have said what they need to say, and had a chance to listen, without interruption, to what you are telling them.
  6. When one twin asks a question, answer that twin directly.
  7. Remember that when interacting verbally taking turns to listen is as important as taking turns to talk.
  8. Remember also to value silence. Pause frequently when you are conveying information. This gives a better chance for information to "sink in", and it also provides opportunities for the child to formulate their next "turn" in the conversation. Children need pauses and "space" to think up what they want to say.