Picture the scene: you’re sat down relaxing one day, when your phone rings. You answer – it’s a good friend of yours. She explains that she needs to predict how happy someone will be in ten years time. She heard that you read a book about happiness, and wants your help. She’s rushed – it’s very important and you only have time to offer one suggestion. What one piece of information is the best way to predict someone’s happiness, ten years down the line?

Really think about this. What would you suggest? Their income level? Whether they’re married? How good their health is? What line of work they’re in? Which country they live in?

The surprising truth is that the most accurate single predictor of how happy someone will be in ten years time, is how happy they are right now. What’s the one thing that stays with you for all this time, and doesn’t change at all? No, not taxes. It’s your genes: the DNA code inside every one of your cells. Your genes are the recipe for how to build you, and research has shown that about 50% of the variation we see in happiness is down to variation in genes.

There’s a common misunderstanding that if something is said to be ‘genetic’, then it is also fixed and unchangeable – this isn’t true. When people talk about genes vs environment, an analogy could be building a house. Genes are the blueprint for a house, and environment is how and where it is built.

Take that blueprint, and give it to different contractors, build it in different locations, different weather conditions, and it will come out differently each time. The houses won’t be completely different – they do have the same blueprint after all – but changes will have to be made. Likewise, a gene doesn’t dictate how something will definitely end up in the real world. Genes are more like instructions for the living things that host them, telling them how to respond to different stimuli they might come across.

For example, at some point in evolution, muscles developed the ability to grow bigger and stronger when they are being worked harder than normal. This helped us adapt to our physical environments, which allowed us to survive. The recipe for this system is contained in the genes. Put simply, it probably goes something like this: “If muscle is under x amount of stress, increase it’s size by y.”

There’s a genetic element to muscle growth. The genes will ‘tell’ the organism how much they should grow by; how much of certain hormones to release, how much protein to synthesise, what stress threshold the muscles need to be under for this process to begin, and things like that. This is all genetic, and so some people find it easier to build muscle than others. But there’s also an environmental element – if you don’t exercise, the genes won’t get activated, no matter how ‘good’ they are. There isn’t a ‘big muscles gene’, but rather, there are genes for a system that makes muscles easier to build – if conditions are right.

Likewise, there isn’t a ‘happiness gene’. It just means that some inherited traits and characteristics are leading us to experience a certain range of happiness levels, if conditions are right. Maybe they trigger more activity in the left hemisphere of the brain, which is associated with positive emotions. Or maybe our inherited personality leads us to do certain things. As an example, social relationships are a source of happiness. Extraversion is a personality trait that leads people to be more sociable. And extraversion happens to be strongly heritable. So while there’s a genetic side to happiness, don’t worry. ‘Genetic’ doesn’t mean ‘fixed’.

Refs:

Lykken, D., & Tellegen, A. (1996). Happiness is a stochastic phenomenon. Psychological Science, 7, 186-189.

Tellegen, A., Lykken, D. T., Bouchard, T. J., Wilcox, K. J., Segal, N. L., & Rich, S. (1988). Personality similarity in twins reared apart and together. Journal of Personality and Social Psychology, 54, 1031-1039.