Moral Foundations Theory (MFT) has popularized the idea that political ideology is based on moral sensibilities. The idea is that, although everyone shares the same core moral intuitions, people vary in how much weight they give to each intuition and this variation is reflected in their political beliefs. Thus liberals care more about Harm than conservatives or libertarians, conservatives care more about Authority, libertarians care more about Liberty, and so on.
Research on the relationship between personal politics and moral intuitions tend to be correlational studies. Participants choose a political label for themselves and complete questionnaires, typically including the Moral Foundations Questionnaire, which asks participants about the relevance of various factors to their sense of right and wrong and how much they agree with various statements. What you get are group means for each moral intuition. Group differences are often modest to moderate, e.g., in one study using the MFQ (0-5 scale), the Fairness group means for conservatives, libertarians, and liberals were 3.02, 3.09, and 3.79, respectively (Iyer et al (2012). Interesting, significant, but not earth shattering.
The Moral Foundations Questionnaire has been found to be a reliable and valid tool for exploring moral domains. Note, though, the word "foundations" implies a causal role for moral intuitions, such that moral priorities give rise to political ideologies rather than the other way around. As noted before, however, these types of studies are correlational and cannot establish causality.
Neither moral inclinations nor political identity are fixed. For instance, in a recent Pew survey, about a third of Republicans reported an earlier point in their lives they had considered themselves Democrats, while 22% of Democrats said they previously considered themselves Republicans. And while moral intuitions seem fairly stable in experimental studies, moral beliefs are pretty easy to change with minor experimental manipulations. Unfortunately I have yet to find research that considers the stability of moral intuitions across the lifespan (not surprising since MFT is a young theory). However, there's plenty of relevant research on the related subject of emotions and age.
The strength of a moral intuition reflects, in part, the intensity of its emotional signal. Emotion is information and it informs us that "this matters". As we get older, emotions tend to become less intense and we get better at regulating how we feel. We develop habits of down-regulating some emotions and up-regulating others - that is, lowering or increasing emotional intensity. Through experience and reflection, we may come to value some emotions over others. We may become adept at changing the subject and moving on. I would imagine as many of us get older, we become less beholden to strength of feeling to guide our actions. We still pay attention to our 'guts' but we've learned that the gut can lead us astray. We learn to step back and look at the big picture.
The big picture is not only about what really matters but also about how things work. People change political beliefs in part because they've come to a different understanding of how the world works. These changes in understanding often come about gradually in response to life experiences and whatever narratives are available that help make sense of these experiences.
How we think the world works influences how we make moral decisions. For instance, we might develop a 'tough love' approach to some social problems because we think it's more effective at reducing these problems than generous aid programs. We might even stifle our own compassionate impulses to better align our actions with our convictions: dampening a moral intuition (e.g., Harm) for the greater good.
Reference:
Iyer R, Koleva S, Graham J, Ditto P, Haidt J (2012) Understanding Libertarian Morality: The Psychological Dispositions of Self-Identified Libertarians. PLoS ONE 7(8): e42366. https://doi.org/10.1371/journal.pone.0042366