For the first time in history, researchers have isolated the parts of the human genome that could explain the differences in how humans experience happiness. These are the findings of a large-scale international study in over 298,000 people, conducted by VU Amsterdam professors Meike Bartels (Genetics and Wellbeing) and Philipp Koellinger (Genoeconomics). The researchers found three genetic variants for happiness, two variants that can account for differences in symptoms of depression, and eleven locations on the human genome that could account for varying degrees of neuroticism. The genetic variants for happiness are mainly expressed in the central nervous system and the adrenal glands and pancreatic system. The results were published this week, in the journal Nature Genetics.
Very few genetic variants have been associated with depression and neuroticism, likely because of limitations on sample size in previous studies. Subjective well-being, a phenotype that is genetically correlated with both of these traits, has not yet been studied with genome-wide data. We conducted genome-wide association studies of three phenotypes: subjective well-being (n = 298,420), depressive symptoms (n = 161,460), and neuroticism (n = 170,911). We identify 3 variants associated with subjective well-being, 2 variants associated with depressive symptoms, and 11 variants associated with neuroticism, including 2 inversion polymorphisms. The two loci associated with depressive symptoms replicate in an independent depression sample. Joint analyses that exploit the high genetic correlations between the phenotypes (|ρˆ| ≈ 0.8) strengthen the overall credibility of the findings and allow us to identify additional variants. Across our phenotypes, loci regulating expression in central nervous system and adrenal or pancreas tissues are strongly enriched for association.
Genetic influences on happiness
Prior twin and family research using information from the Netherlands Twin Register and other sources has shown that individual differences in happiness and well-being can be partially ascribed to genetic differences between people. Happiness and wellbeing are the topics of an increasing number of scientific studies in a variety of academic disciplines. Policy makers are increasingly focusing on wellbeing, drawing primarily on the growing body of evidence suggesting that wellbeing is a factor in mental and physical health.
VU Amsterdam professor Meike Bartels explains: “This study is both a milestone and a new beginning: A milestone because we are now certain that there is a genetic aspect to happiness and a new beginning because the three variants that we know are involved account for only a small fraction of the differences between human beings. We expect that many variants will play a part.” Locating these variants will also allow us to better study the interplay between nature and nurture, as the environment is certainly responsible – to some extent – for differences in the way people experience happiness.”
Further research is now possible
These findings, which resulted from a collaborative project with the Social Science Genetic Association Consortium, are available for follow-up research. This will create an increasingly clearer picture of what causes differences in happiness. Professor Bartels points out that “The genetic overlap with depressive symptoms that we have found is also a breakthrough. This shows that research into happiness can also offer new insights into the causes of one of the greatest medical challenges of our time: depression”. The research effort headed by professors Bartels and Koellinger is the largest ever study into the genetic variants for happiness. It was successfully completed thanks to the assistance of 181 researchers from 145 scientific institutes, including medical centres in Rotterdam, Groningen, Leiden and Utrecht, and the universities of Rotterdam and Groningen.