If you're happy with life and the world around you, who gets the credit? Likewise, if things are dreary and feel unhopeful, who gets the blame?

Some people feel they control their own happiness, while others feel helpless.

And for years, one well-known scientific theory backed the belief that we don't have much say in our well-being. The "happiness pie chart" proposed that 50% of our happiness is determined by our genes, 40% by our activities and 10% by our life circumstances. The idea was originally suggested by researchers in 2005, and has come to be known as the Sustainable Happiness Model (SHM).

happiness pie chart According to the model, we only control 40% of our happiness. (Photo: Smcg8374 [CC BY-SA 3.0]/Wikimedia Commons)

The pie was interpreted to mean that your genetics play the largest role in how happy you are. If your parents are generally upbeat, see-the-sunny-side people, then there's a good chance you are too. Likewise, if they passed on their negative dispositions, that's what you have to deal with.

Life circumstance has a small but notable impact on happiness, determining about 10%. Circumstances include everything from age, gender and ethnicity to where you live, marital status, your job, income, health and religious affiliation. It also includes a range of life events from winning awards to being involved in trauma like car accidents.

But genetics and circumstances aside, the choices we make in life — what we eat, how we spend our time and with whom — have a big impact on how happy we are.

Activities matter

couple walking dog in woods The choices you make — how you spend your time and with whom — have an impact on how happy you are. (Photo: Monkey Business Images/Shutterstock)

The happiness model has been studied and dissected for 15 years, but not necessarily correctly. Kira M. Newman points out in Greater Good Magazine that the simple formula represented in the chart isn't as simple as reported.

"These numbers don’t represent how much of our individual happiness comes from various sources, but how much of the differences among people (in general) do. If your happiness is 8/10, you can't say that 3.2 points of that is determined by your activities; you can merely say that just under half of the average gaps between your happiness and other people's comes down to what activities everyone is doing," she writes.

That said, however, researchers say the general idea makes sense.

The late psychologist Christopher Peterson was one of the founders of the positive psychology movement. He addressed the issue, writes Ed Batista, an executive coach.

"One of the frequently cited conclusions from positive psychology research is that happiness results from a combination of genetics, circumstances, and voluntary activities. This is reasonable enough. Indeed, it is a virtual tautology that applies to most any human characteristic," he wrote. "Some positive psychologists go further and propose a happiness formula, typically a weighted sum of its components, with weights based on research with large samples of individuals. A representative set of weights is 50% genetics, 10% circumstances, and 40% voluntary activities. Again, this is reasonable enough, reflecting the research literature as I read it, although the exact weights are always a function of the samples from which they are derived."

However, Peterson concluded, "So where am I going? To the conclusion that it is thoroughly unreasonable to think that we can parse the happiness of an individual, in the moment or in general, in the same way that we can parse the happiness of samples of individuals."

Just keep trying

happiness mural in San Francisco Happiness can be anywhere, as this mural in San Francisco implies. (Photo: Eric E Castro [CC BY 2.0]/Flickr)

Recently, the happiness pie chart has had its detractors. They point out that genes, circumstances and activities can overlap and impact each other.

For example, if you have the gene for leadership but aren't in a work environment where you can take on that role, then how can you use those skills, asks Todd B. Kashdan Ph.D. in Psychology Today.

"Be skeptical," Kashdan writes. "These perfectly round numbers raise more questions than answers, and as of today, I still don't trust them."

Two of the authors of the original study have recently said their model has "valid critiques," they write in The Journal of Positive Psychology.

But the takeaway is that people can still impact their own happiness. In fact, our actions may not have as much of an effect as originally thought (maybe as little as 15%, according to one study in the Journal of Happiness Studies). The key is to keep trying.

"Although the pie chart part may have outlived its usefulness, we stand behind the central premise of the SHM, and the supportive research it spawned," the researchers write. "Happiness can be successfully pursued, but it is not 'easy.' "

Mary Jo DiLonardo covers a wide range of topics focused on nature, health, science and anything that helps make the world a better place.

How much can you control your happiness?
Experts doubt the theory behind the 'happiness pie chart,' saying what you really can impact is how happy you are.