The results are published in Nature Mental Health. Based on the questionnaires, wellbeing (or happiness) was found to be highly predictable, with personality, optimism, health, loneliness, and social relationships being particularly important. Another key finding was that happiness in adulthood is strongly influenced by how happy we are as teenagers: generally, people's wellbeing levels are fairly stable throughout their lives. Researchers had access to data from childhood and adolescence, which proved to be especially valuable; even traits around the age of 3 were found to influence happiness in adulthood.
Unique combination of data
What makes this study unique is that survey data from participants of the Netherlands Twin Register (NTR) from childhood to adulthood – collected over the last three decades – was combined with genetic data. In addition, information about the neighbourhood where participants lived at the time of the survey was used. This was achieved by linking the participants’ postal codes to neighbourhood data from the Geoscience and hEalth Cohort COnsortium (GECCO). GECCO was established in 2018 with the aim of making objective data about the environment (such as air pollution, proximity to amenities, and the population and housing composition of the neighbourhood) more accessible to researchers. Ultimately, the researchers had access to more than 2,500 variables obtained through questionnaires and over 700 variables at the postal code level. Previously, it was not possible to use such large amounts of data for prediction, but the researchers employed modern machine learning models capable of handling this complexity.
Housing characteristics of the neighbourhood are important
Although neighbourhood characteristics at the postal code level were less important than the questionnaire data, they still played a significant role for our wellbeing. “When we looked in more detail at which specific factors mattered, one thing stood out: housing characteristics of the neighbourhood were particularly important. For example, the number of newly built social housing units and the number of homes sold in a given year were important,” says lead researcher Dirk Pelt, assistant professor at the department of Biological Psychology. “This was true for the current neighbourhood, but also for the neighbourhood where one grew up in. Especially in light of the current housing crisis in the Netherlands, this is an important finding.”
Interestingly, the genetic data available in this study did not predict people’s wellbeing. This may be due to the fact that the researchers only used common variations in DNA to make predictions. As a result, we may miss important information from more rare or more complex parts of the DNA.
According to the researchers, the study has important implications for promoting people’s happiness and wellbeing. Meike Bartels, professor in Genetics and Wellbeing says, “This research reflects the tremendous power of large, long-term studies. Such data, as collected in the Netherlands Twin Register, allows us to make accurate predictions. Regular monitoring of how people feel and what is happening in their lives is therefore important.” Furthermore, the results suggest that the importance of neighbourhood housing characteristics deserves more attention in efforts to enhance people’s wellbeing.