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Stockholm University sheds new light on family life

Stockholm University sheds new light on family life
Photo: Kristin Lidell/
Researchers at Stockholm University have used the data tied to Swedish personal numbers to answer complicated questions about family dynamics and other population processes.

The ten-digit Swedish personnummer is the Swedish national identification number assigned to a person when they register as part of the population with the Swedish Tax Agency (Skatteverket) — whether that’s at birth or after relocating to Sweden for an extended period of time. When it was introduced in 1947 it was probably the first of its kind covering the total resident population of a country.

It also presents unique research possibilities. Unlike other countries with similar systems — such as the US social security number — Swedes provide their personal numbers for pretty much everything. From starting school to income information, they’re a big part of everyday life and can reveal a lot about the population.

The number is used by public authorities, in the healthcare system, schools, and universities (both public-run and private). The personal number is also used by banks for tax purposes and mandatory customer identification, and by insurance companies for car liability insurance and for medical travel insurance coordination.

Not 'big brother'

Other companies often ask for someone’s personal number in conjunction with pre-paid services, like a telephone subscription, to check the person's credit records.

With selected administrative data at their disposal, it’s no surprise researchers at Stockholm University have used it to answer complex questions in more detail than ever before.

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But don’t worry, it’s not as “big brother” as it sounds. Researchers don’t have access to the actual personal numbers – only an anonymized key.

Nor is the data that’s available to them through the government administrative registers of the sensitive kind. It just means researchers can look at which factors may produce different outcomes for people with different backgrounds when it comes to education levels or receiving government benefits, for example.

Most recently, the university has published three separate studies exploring topics concerning family dynamics.

Does sibling spacing matter?

The first example of recent research, a study conducted by Kieron Barclay and Martin Kolk of Stockholm University’s Department of Sociology, considers whether spacing between births has any impact on long-term cognitive, educational, and socioeconomic outcomes.

It was previously believed that a short birth interval (in layman’s terms, a woman becoming pregnant again shortly after giving birth) might have negative effects on both children.

This was in part because the mother may not have had time to physically recover from the first birth, resulting in issues like low birth weight. Another concern was that neither child would get the full attention required in their formative years. However, Barclay and Kolk have used register data to show that this isn’t the case.

Photo: Simon Paulin/

“In our new study, we find – in contrast to previous research – that birth spacing does not matter for how long people spend in education, how their cognitive ability develops, or how they perform in the labour market”, the pair write on Socio(b)log.

The researchers followed individuals born between 1960 and 1990 from birth through education and into the labour market. They looked at factors including high school grade point average, IQ, number of years spent in education by age 30, and government welfare support received by age 30.

They found that birth spacing has no effect for long-term outcomes in Sweden, and suggested previous negative outcomes observed in relation to short birth spacing could be a result of other existing health and socioeconomic disadvantages.

The researchers note as well, however, that since Sweden is a highly developed country, with excellent healthcare and a good standard of living, the effects of birth spacing may be more pronounced in less developed countries.

Identifying with one's homeland

A second Stockholm University study sheds light on another timely topic: whether young Swedes with a foreign background are able to culturally identify with both their parents’ homeland and Sweden.

To gather the data, researchers conducted surveys within the target groups and combined the results with population register information like area of residence and school performance.

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Researchers focused on Iranian and former Yugoslavian youths, two target groups that are sizeable enough to represent a range of possible experiences. They found there was no conflict between identifying with both their parents’ homeland and Sweden. In fact, quite the opposite.

“Actually, there’s somewhat of a tendency that the more strongly you identify with your parents’ homeland, the stronger identification you have with Sweden,” explain Jens Rydgren, Stockholm University Professor of Sociology of and co-author of the study.

Single parents and stability for kids

A final study looks at whether children who are living full-time with a single parent are more or less likely to feel stress several times a week than if their parents share physical custody. It was previously thought that this living situation may create an unstable and stressful environment for children.

“Those who pointed to it earlier have built their concerns on theoretical assumptions, rather than empirical research,” says Jani Turunen of the Demography Unit at Stockholm University’s Department of Sociology and author of the study.

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Turunen gleaned his insights by combining data from the Surveys of Living Conditions in Sweden from 2001-2003 with population registry data. He found that children who live full-time with one parent are more likely to feel stressed than children who live in joint custody situations.

“In other words, living with both parents does not mean instability for the children,” he explains.

Turunen explains the findings may be due to the fact that children who spend a lot of time away from one parent lose resources such as relatives, friends, and money connected to the other parent. Children sharing residence, on the other hand, can maintain a stronger relationship to both parents compared to those who see one of them on weekends or less frequently. Previous research has shown children may also worry more about the parent they don’t see regularly, which can be the cause of further stress.

The new study indicates that contrary to the opinion that shared physical custody is undesirable, it actually results in less overall stress for the child.

“It's just an adaptation to another housing situation, where regular relocation and good contact with both parents equals to stability,” he says.

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This article was produced by The Local Client Studio and sponsored by Stockholm University.