The crucial role of relatives in shaping our lives

New Study uncovers kinship insights from Sweden's family records


Relatives are important in our lives. Family members like cousins, grandparents, and grandchildren are part of our social circle and can give us a lot of support. They help with raising children, taking care of the elderly, and even provide financial help when needed.

For the first time ever, a comprehensive examination of kinship in a modern society has been undertaken, thanks to Sweden's distinctive records that encompass information on the entire population. 

In a study conducted by researchers at Stockholm University, the intricacies of family structures in Sweden have been unveiled. This extensive research, published in the journal Demography, provides insights into the number of relatives Swedes have and how it fluctuates across different stages of life.

Martin Kolk and a group of researchers at Stockholm University have documented for the first time how many relatives Swedes have. How many family members do people in Sweden have? And at what age do families tend to be the biggest?  

“There has been a lack of knowledge about how many kin people have in modern societies, and this information has never before been collected for an entire population. There have not been clear answers to questions such as how many cousins you have in Sweden or other countries,” says Martin Kolk, Associate Professor in Demography at Stockholm University’s Demography Unit and lead author of the study.

Insights from Extensive Data

In order to study family networks, researchers need to use very large sets of data that are both extensive and reliable. In Sweden, they have access to special records that contain information on the entire population, allowing them to create networks that connect individuals to all their living relatives, going back many years.

This study used information from official records in Sweden to understand family relationships. The researchers looked at data from all people who were born in Sweden and lived there in 2018. They used birth records to create family networks and count the number of relatives, such as grandchildren, children, nieces, nephews, siblings, cousins, parents, parents' siblings, and grandparents, using unique identification numbers. The researchers then analysed the data to find the average number and distribution of different types of family members in Sweden. Since the data only includes information within Sweden's borders and for people born in Sweden, the study focused on Swedish-born individuals. However, for people with foreign-born parents, information about grandparents may be missing. The study includes various figures that show how family members are distributed and the average number of each type of relative.

The number of relatives one has in life is influenced by the stage of the life cycle they are in. As individuals grow older, they tend to have more relatives in the descending line, including grandchildren. Conversely, younger individuals typically have more relatives in the ascending line, such as parents. People in the middle of their lives often have a diverse range of relatives, including siblings and cousins who belong to the same generation. In Sweden, for example, individuals in the middle of their lives have an average of 8 cousins, with nearly 30 percent having 11 or more cousins. This highlights the varying dynamics of family structures across different stages of life.

According to the study, Swedes in their mid-30s have an average of 20 relatives, while young children have around 15 relatives, and 70-year-olds have approximately 10 relatives.


“How many relatives you have is affected by many different things, such as differences in childbirth over time, when in life you have children, differences in life expectancy, and age differences between partners. All of these things can differ greatly between different families, and have also changed a lot over time,” says Martin Kolk.

Rare cases: Individuals with no living relatives

It is uncommon to find individuals who have absolutely no relatives in their lives, and this usually occurs in exceptional cases among elderly individuals. The family networks of both men and women are generally quite similar. As time passes, it is common to observe a higher proportion of relatives who are the result of separations, such as half-siblings.

“How many relatives you have differs very much between different individuals and at different ages. Most living relatives are found between ages 30 and 40. We see large variation in how many kin you have. The twentieth with the least kin have only 3–4 relatives, while the twentieth with the most kin have over 45.”

Relatives important for life chances

This newfound knowledge contributes to a deeper understanding of the role of relatives in modern society, offering valuable insights into the complexities of family life.

“By documenting kinship we know more about a previously unexplored part of Swedish family life that is an important part of many people’s lives. Social science research has also shown that relatives are more important for life chances in modern societies than previously thought, and therefore it is important to document how many kin people have.”

“Sweden has the longest records of any country with modern digitised population registers starting in 1968, with parent-child links from 1932. The state has been collecting national population back to 1749. This is both very useful for administrating the Swedish welfare state, and also make internationally unique research possible, such as this study,” says Martin Kolk.