Field of Science

Why young adults change their religious beliefs

Your religious beliefs, like many aspects of personality, tend to crystallise in your late teens and early adulthood. It's a period of tremendous change but, once set, few people undergo and radical changes.

Even so, some kids change, while others do not. It's interesting to speculate on why that might be. What separates the changers from those who stay the same? Is it genetics, or is it environment?

A recent study has looked at this using data from two twin studies in Colorado, USA. The basic idea is simple: they measured religiosity at around 12-18 years old, and then again around 5 years later.

By comparing identical twins with non-identical twins, you can estimate the importance of three factors contributing to the change:
  • Genetics (what's shared by identical twins but not non-identical ones),
  • Family or shared environment (what's shared by twins after you take out the genetic component, but not shared by individuals not brought up together)
  • Non-shared environment (what's left, which is basically whatever it is that causes twins to be different).
Now, it has to be said that there are a lot of caveats to these kinds of studies. The gene-environment interaction is complicated, and the effect of genes in one environment likely differs from the effect in another - including another genetic environment (i.e. the same gene will have different effects in different people).

There's an additional problem when linking genes to personality. The classic example is genes for skin colour. Your skin colour affects the way people treat you, which in turn affects your personality. Gene linkage studies would show that your personality is genetically determined, whereas in truth its the environment (i.e. social prejudice) which is causing the effect!

All in all, lessons from gene studies in Colorado, where the population is mostly religious but undergoing change, do not necessarily apply to Pakistan or Sweden.

That said, take a look at what they found. For those Colorado kids who kept their religious beliefs as they moved into adulthood, the major influence was their family. Not too surprising- your family environment is a major, constant factor.

Interestingly, however genes only play a minor role - especially when it comes to the importance of religion in their lives. Keeping the faith is largely a function of family pressure.

Looking at what lies behind changing religious beliefs, you can see that the external environment (the stuff that one twin is exposed to but the other is no) plays a vital role. Change is driven by outside influence.

But it's also driven by genetics - and to a greater extent than religious stability. What this seems to indicate is that some effect of genetics is critical to changing beliefs.

In the case of these Colorado kids, the most common change (in common with kids elsewhere in the USA) was a decrease in religious attendance and also in the importance attached to religion.

So some kids are genetically predisposed to shift their beliefs. Unfortunately, what this study doesn't tell us is why. Perhaps these genes somehow lead to a rejection of religious worldview. That's certainly a possibiliy.

But I wonder whether perhaps some kids are just born to be different. Perhaps these kids are becoming non-religious because it shocks the old folks. Perhaps, in a world of atheists, these would be the kids picking up religion!

ResearchBlogging.orgButton TM, Stallings MC, Rhee SH, Corley RP, & Hewitt JK (2010). The Etiology of Stability and Change in Religious Values and Religious Attendance. Behavior genetics PMID: 20711848

Creative Commons License This article by Tom Rees was first published on Epiphenom. It is licensed under Creative Commons.


  1. "becoming non-religious because it shocks the old folks"

    Shocking people had nothing to do with my recent non-belief; my non-belief is due to careful examination of different world religions, including my own.

    I was raised in Colorado and I was a Catholic for 33 years. Once the internet became prevalent in the late 90's I started studied world religions in depth and slowly came to the conclusion that there is no proof for the existence of any gods, including the one I believed in. All religions are man-made, they have to have 'faith' because they have no proof!

    This was not an easy transition and took a few years to come to terms with but my life has new meaning now that I don't have this delusion confusing my view of the world.. and I'm not alone, there are thousands like me and growing.

    The internet is where religions go to die.

  2. Or maybe atheists lack faith because they have a stronger urge to understand how things work / why things are true (curiosity gene), or maybe because atheists are more willing to challenge their world views and test drive alternatives as it were (intellectually adventurous gene). Or maybe OP is right. Needs moar data.

  3. Maybe there is a genetic component to individually perceived security? I can totally see that. Are there studies about the connection between genetics and the Big 5?

  4. "But I wonder whether perhaps some kids are just born to be different. Perhaps these kids are becoming non-religious because it shocks the old folks. Perhaps, in a world of atheists, these would be the kids picking up religion!"

    I'm very glad you put this in! I was going to write it myself until i read it there. Obviously it's not a major reason for changing, but given the ages of the children concerned it may play a factor.

    Also was presence/attendance at college or uni counted? Going to uni, and meeting all sorts of people from different places who thought different things was a MAJOR part in shaping my thoughts, ideas and beliefs.

    LOL @ the curiosity gene :D

  5. @why young adults change religious believes
    when we are young its our parents we are dependant upon ,we do as they do and consider them right
    but as our conscious grows and our ability to think grows and we are exposed to other views, our understanding starts changing and we start to build a conceptual world of our own and given todays scientific progress orthodox believes are bound to change...
    @religions are man made
    *(for a better understanding see: )
    what i blame atheist is for not giving religion its proper due ....they listen to other atheists a lot and show biased attitude to theists.
    I am a muslim and belong to ahmadiyya community(we have a different stance than orthodox muslims) ....we believe that god still talks to the chosen ones and gives them his support.revelation is a living reality and is not just a story.the founder of our communoty claimed that god has sent him as the messiah whose advent has been prophesized by all the world religions.he claimed that god reveals to him and stands by him...
    History of our community is a proof of his claims...
    Other than this why i beleive islam is a true religion is because:
    1)it presents a teaching that just not makes a good relationship between God and man but also teaches the method of peaceful relationships between man .
    2)islam doesnt impose teachings,it tells by giving logic and making understand
    3)its dosent rely on old stories and asks to experience and tells that a part of every truth is visible in this world and can be experienced
    4)its doesnt just crushes emotion albeit it channalizes them in a progressive way
    5)it just doesnt tell me to take care of my self but sets a code for every relation.ensures rights of every person
    6)it completely satisfies me about the presence of god in the light if new scientific discoveries

  6. Anon - looks like a clear case of external environment leading to a change in beliefs! But then everyone has access to the internet, but not everyone uses it in the way you do.

    To me, that's the important thing to remember - also what darksmiles,verquer and labrat said. The temptation is to think that the genetic link is something directly to do with religious beliefs. But very likely it's actually something more indirect - like approach to life, questioning,wanting to stand out from the crowd.

    Which is why I highlighted that the same genes could have a different effect in Sweden!

  7. Craig, they will have had a range of religious experiences in the home environment that are, as far as we can tell, representative of what kids growing up in Colorado would experience.

    Some will be good, some will be bad. No doubt the good experiences would encourage the kids to maintain their religiousness. That is, in fact, exactly what this study is saying. Family environment is critical for those who maintain their religious beliefs.

    On the other hand, family environment seemed to be unimportant as a driver for switching out of religion. It wasn't the family that drove these kids away from religion, it was their experiences in the outside world.


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