Environmental and genetic factors shape your attitude.  Current theory is the impact of nature versus nuture on personal attitudes is not a fixed factor.  It depends.

The type and magnitude of environmental factors can override your genetic template or complement it or even reinforce and exaggerate your basic natural proclivities.

A lot of this information comes from studies with identical twins, particularly those separated at birth and growing up in very different environments.

Changing and adapting your attitude

Through your adolescent and teenage years your foundational attitudes are formed.  These are influenced by your surroundings (nurture) and your genetic template (nature).

Research indicates the balance between nature and nuture influences varies greatly by individual.  This tends to support the theory we control our attitudes to some extent (nurture influences).

Although we often believe you cannot change how a person thinks once they have formed their base personality and personal value system, (usually by their 20’s) you actually can teach an old dog new tricks.

“Tricks” are in fact just behaviors.  Your behaviour can be influenced by others or your own desire to change at any time.  So if others want you to, or you want to, behavioural change can occur.

We often view behavioural change as reflective of our attitude, in fact your value based attitude, your personality might not change (probably doesn’t) at all, just your behaviour.

Conclusion

We can change our behaviour throughout our lives, our base attitude though is probably fixed by our early twenties.