Twin Identity and Closeness: What Recent Research Does and Doesn’t Say

Many twin families end up asking two questions at once: are our twins too wrapped up in each other, and will giving them space damage the bond? Recent research suggests those two worries are less opposed than they sound.

Can Twins Become Their Own Person and Still Stay Close?

Yes. In a 2024 interview study, most twins wanted both independence and closeness, and they did not treat the two as opposites.

Researchers led by Laurie Kramer at Northeastern University interviewed 40 college students in 20 twin pairs, 11 identical and nine fraternal, with an average age of 19.7. Each twin was interviewed individually about their identity and their relationship with their twin (Kramer et al., 2024). In 15 of the 20 pairs, the twins put a priority on developing distinct identities, and many saw college as the right time to do it. The pairs who leaned toward staying similar were identical twins who wanted emotional closeness and support and who attended the same college.

The researchers describe deidentification, the deliberate seeking of differences from a sibling, as a gradual process rather than a break. Twins took steps toward independence while trying to keep the closeness, trust, and reliance they had long had.

Limits. The sample was small and made up of college students who chose to take part. The study does not show that separation causes independence, that staying together holds development back, or that the pattern applies to twins at other ages. It concerns emerging adulthood, not the whole adult lifespan.

For a clinician’s view of what it can look like when one twin loses touch with their own instincts inside the twinship, see Dr. Joan Friedman’s The Importance of Forming Your Own Identity as a Twin.

Do Identical Twins Struggle More With Identity Than Fraternal Twins?

In one recent study of early adolescents, they did not: identical and fraternal twins scored about the same on measures of self-esteem and adjustment.

A Czech study of 336 twins aged 11 to 15 (168 pairs, 32 identical and 136 fraternal) used standardized questionnaires on behavioural adjustment, school adjustment, and self-esteem (Kargerová, 2026). Identical and fraternal twins did not differ significantly on any of them, and the group’s scores fell close to norms for Czech adolescents in general. Small focus groups of three pairs described two things at once: the emotional security of having a twin and a struggle to be seen as an individual.

Limits. Only 32 identical pairs took part, so the study had limited power to detect differences, and a result that is not statistically significant does not prove the groups are the same. The twins reported on themselves, zygosity was based on parents’ reports without genetic testing, and the sample came from one country. The study did not measure rivalry and did not compare twins in the same school with twins in different ones. It is best read as a reason not to assume that being identical, on its own, predicts identity trouble.

How Do Roles Like “the Leader” and “the Follower” Form Between Twins?

Roles often appear early, and one large study suggests they can outlast the circumstances that created them.

Nurses who work with multiple-birth families in Finland were asked about twins under age seven. In their written answers, they described twins taking on roles such as the one who takes up space, the decision maker, the follower on the sidelines, the helper, and the one who receives help, and twins who were either bold and visible or who withdrew into the background (Heinonen et al., 2026). This was a survey of 72 nurses, not 72 twin pairs, so it reports what professionals observe. It does not show how common these roles are or whether they cause problems.

A longitudinal study of 1,521 twin pairs followed from about age 3 to ages 8 to 9 looked at how roles form when the twins’ development differs. When both twins developed typically, or both had a similar developmental condition, parents saw no difference in dominance. When only one twin had a developmental difference, parents generally perceived the typically developing twin as more dominant, and that perception continued through childhood even after the original difficulty had resolved (Segal et al., 2025). The authors also note that a twin seen as less dominant with their co-twin may still show dominance in other settings.

Limits. These are parents’ perceptions, not independent observations of what happens between the twins, and dominance is not the same as bullying. The study ends at ages 8 to 9 and does not show that roles are permanent or test any way of changing them. It draws on the same group of families as the temperament study below, so the two are not independent confirmations. For how roles and comparison show up at each age, see Twin Rivalry at Every Age.

Does Temperament Affect How Close Twins Are?

Twins who were more alike in temperament were rated as closer, whether they were identical or fraternal.

In the same Israeli longitudinal study, researchers followed twins from about age 3 to ages 8 to 9, using reports from 1,547 mothers and 536 fathers (Segal et al., 2024). Twins who differed more in temperament were rated as less close at every age, and that link held beyond the difference between identical and fraternal twins. Identical twins were rated as closer overall, but twin type on its own did not significantly predict conflict. Twins whose negative emotionality, meaning how easily and strongly a child gets upset, grew further apart over time also showed more conflict, a link that appeared mainly by ages 8 to 9.

Limits. The 1,547 and 536 are parents who responded, not twin pairs, and both closeness and conflict were reported by parents. The study found associations and could not tell which comes first: similar temperaments may bring twins closer, or closeness may make them more alike. It does not suggest that parents should try to make twins more alike. For more on how rivalry and comparison fit in, see Why Twins Fight.

Does Separating Twins at School Help Their Identity?

The best available evidence finds no strong average effect either way, which does not support a fixed rule about separate classrooms.

A large study of classroom placement used data on twin pairs from Quebec and the UK, more than 9,000 pairs according to the researchers’ university, across ages 7 to 16 (White et al., 2018). It compared twins taught in the same class with twins taught in different classes on academic achievement, several cognitive abilities, and motivation. There was almost no sizeable positive or negative average effect of separation. At age 12 in Quebec and age 16 in the UK, twins in the same class were slightly more similar in achievement, but the effects were weak, and it is unclear whether separation or other factors explain them. The authors concluded that educational policy should not impose rigid rules either way, and that the choice should reflect each pair’s needs (Goldsmiths, University of London).

Limits. That study measured schoolwork, thinking skills, and motivation. It did not measure identity, self-esteem, or emotional wellbeing, which the researchers say still need to be studied. An average of “no effect” can also hide individual children who do noticeably better or worse in one arrangement; the authors say they are not claiming that separation has no effect on the children involved. The Czech and college studies above did not compare placements at all, so none of the newer research answers this question directly. For a clinician’s account of why a change of school should not be treated as a fix by itself, see Dr. Friedman’s Separating Twins in Middle School: Why the Quick Fix May Backfire.

What Can Parents Do With This Research?

Treat each twin as an individual and check your assumptions, rather than following a rule for either closeness or separation.

The suggestions below are editorial guidance. They are not findings from the studies above, and none of these studies tested them.

• Ask each child what they want. The college twins had clear preferences about closeness and independence, and those preferences differed between pairs.
• Give each child a turn. When you ask both twins a question, wait before either answers, and hand the question back if one habitually answers for the other.
• Check whether an old role is still needed. A role that began for a good reason, such as one twin needing extra help early on, may still be assigned after the reason has passed. Look for settings where each child leads.
• Notice temperament. Twins who handle frustration very differently may need different responses from you, and may not feel as close as a pair who are more alike. That is not a problem to fix.
• Support any change. A new class, school, or living arrangement is easier with time and preparation, and a child who seems persistently withdrawn, low, or anxious is a reason to ask a professional, whatever the placement.

What Does This Research Not Tell Us?

It does not tell us why these patterns arise, how common they are, or which parenting choices change them.

• Most of the studies are small, or rely on parents’ or nurses’ reports rather than direct observation.
• They come from different countries and age groups: Israeli children to age 9, Finnish nurses describing twins under seven, Czech adolescents, and American college students.
• They report associations. None tested whether a parenting strategy changes closeness, roles, or identity.
• The two Israeli studies use the same group of families.
• None of the studies covers twins beyond their early twenties.

That is a reason for caution, not for ignoring the findings. Taken together, they point in the same direction: twins are not all alike, and closeness and independence can grow together.

This article summarizes the peer-reviewed studies cited in the text and draws on the work of researchers named there. Content on Twins Magazine is produced using an AI-assisted editorial process and reviewed by a human editor before publication.