I posted the question "Is 50% of a happiness determined by genetics?" on Skeptics but realize I don't fully understand the claim. What does it mean that 50% of happiness is determined by genetics?

Does it mean that each time a person is happy, 50% of the reason they are happy is because of genetics? How can that possibly make sense as happiness is a human construct so why wouldn't the genetic factor apply the same to other emotions like sadness?

Is an example of how genetics determines happiness, that someone is predisposed to liking chocolate, so if they're happy when eating chocolate cake, genetics is 50% of the reason they are happy? Is that the claim?

Does this mean that an unhappy person can't do that much to become happy?

EDIT: would it be correct to say a person can change their level of happiness by +/-50%? Is this what the claim is saying?

TL;DR does the statement mean a person has at most 50% control over how happy they are?

CBS New York reports on research presenting this claim.

  • $\begingroup$ Could you further elaborate on what is unclear about the answer which was provided to you at Skeptics? It seems to go a long way at clarifying what the '50%' means? $\endgroup$ – Steven Jeuris Apr 29 '16 at 8:00
  • $\begingroup$ @StevenJeuris skeptics.se is to verify the integrity of the claim. I don't understand the claim itself. For example, is the claim saying 50% of the reason you don't like getting a speeding ticket is because of genetics? $\endgroup$ – Celeritas Apr 29 '16 at 16:57
  • $\begingroup$ @StevenJeuris in summary I'm wondering does this mean a person has at most 50% control over how happy they are? If no, what does it mean? $\endgroup$ – Celeritas Apr 30 '16 at 0:08
  • $\begingroup$ As stated in the answer on Skeptics this seems to be better stated as: "50% of the variance in the population can be explained by genetic differences." It is a measure of how accurate a statistical model could be, if it only considered one factor. " In case you do not know what "x% of the variance in the population can be explained by a genetic difference" means, perhaps you should phrase your question more generally as such, only using happiness as an example. $\endgroup$ – Steven Jeuris Apr 30 '16 at 15:12
  • $\begingroup$ If I am not mistaken you are interested in methodology? How did they measure the 50%? Where does the number come from? What the statement means you can only interpret if you understand what the number means. $\endgroup$ – Steven Jeuris Apr 30 '16 at 15:21

The statement 50% of happiness is determined by genetics is presumably talking about heritability estimates.

It is probably talking about the percentage of variance explained by genetics.

These estimates are commonly estimated using twin studies. For example, you administer a survey to people that ask a bunch of questions about how happy they feel. There are a variety of measures (e.g., life satisfaction measures, quality of life measures, measures of tendencies to experience positive and negative emotions). If you administer these measures to twins, some of which are fraternal and some of which are identical, you can compare the degree to which the overlap in happiness scores increases in the identical over the fraternal twins.

A wide range of theories of well-being suggest that most people are happy most of the time. There is also theory to suggest that a person's emotional tendencies (e.g., see neuroticism, extraversion, well-being, and so on) are quite stable over long periods of time (i.e., over many years). So this does suggest, that at the very least, it is unusual for someone's emotional tendency to change dramatically over time.


I can think of two ways this can work (though not sure of 50% or more or less): (1) The "environment" to support a happy mind would, among other things, constitute a healthy body. And a body being healthy does depend, among other things, on genetics. (2) The predisposition of an individual to feel happy, given a suitable stimulus might depend on genetics; probably some kind of "happiness" gene!


I think the idea is that genetics regulate neurochemistry and therefore daily mood.

For example--it's likely that some people naturally experience more pleasure due to the calibration of their dopamine and serotonin systems.

Habits of mind may also play a role, but almost certainly a smaller one than genetics do.


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