Creationism, climate denial and anti-vaccination rage: long before the measles outbreak in the US, a deep mistrust of scientists infected some strands of the American conservative movement.

Conservatives are not alone in their rejection of scientific experts and evidence. But the sentiments this week from potential Republican contenders for president – first New Jersey governor Chris Christie in London, then Kentucky senator Rand Paul wagging his finger during a television interview, then a cavalcade of clarifications – have exposed a number of tendencies in American conservatism.

There is the deep resentment of government. And a fierce concern for family privacy. More and more conservatives have a strong libertarian streak. But the aversion to vaccinating children – and the departure from mainstream thinking on public health and other issues – is not really a question of science, experts on the movement said. It’s about the clash between science and deeply held beliefs.

“As with any kind of science denial, it’s never the science itself. It’s these cultural fears,” said Joshua Rosenau of the National Center for Science Education.

On evolution, conservative mistrust stems from the clash with the very foundations of morality for believers – that humanity was created in its present form by God.

On stem cell research, it’s the idea of destroying human embryos that causes concern.

On climate change, it’s the argument – exploited and propagated by fossil fuel interests – that government has no place telling companies what to do.

And on vaccines, as on home schooling and sex education, anti-science sentiments largely have to do with the idea that parents – and parents alone – are the ones who should make choices for their children.

“They don’t want the government telling them what to do,” said Ronnee Schreiber, who teaches gender and politics at San Diego State University. “It’s about being anti-government regulation and ‘preservation of the privacy of the family’.”

Rosenau said some studies suggested that those confronted with evidence that contradicted deeply held beliefs may become more sceptical of unrelated scientific claims.

Creationists can be drawn to climate denial or mistrust of vaccines – even though there is universal acceptance of climate change by the world’s top scientists and the eradication of measles through mass vaccination campaigns is seen as a singular public health achievement.

But there is no firm evidence that Republicans are more distrustful of vaccinations than Democrats – or, leaving aside party identification, that conservatives are less likely than liberals to protect their children from disease.

The Pew Research Center, in a poll released last week, found two-thirds of Americans supported mandatory vaccines. But there was a deep strain of suspicion among those under 30 years old, with 41% thinking vaccines should be a parental choice.

More than one-third of Republicans polled thought vaccines should be left up to parents – compared to 26% in 2009. But the figure was about the same among voters who called themselves independent in the newest poll.

Some 22% of Democrats thought parents should decide on vaccines, compared with 27% in 2009.

A 2013 survey showed 26% of Republicans believe the now-demolished claims that vaccines cause autism – compared to 16% of Democrats.

But other research showed no real political divide among the outliers who fear childhood vaccinations.

Paul, a libertarian Republican, is an eye doctor, but his comments insisting that most vaccines “ought to be voluntary” and citing “many tragic cases” run counter to the guidelines of the American Medical Association, which says physicians have an ethical responsibility to encourage universal childhood immunisation. But the anti-vaccination movement much more typically skews to the left.

The environmental lawyer Robert Kennedy Jr dismayed many colleagues when he refused to let go of the argument that preservatives used in vaccines caused a spike in autism – long after those claims had been discredited.

Religious and social conservatives did object to the HPV vaccine, which some on the right claimed would encourage young girls to have sex.

Fiscal conservatives lashed out when Barack Obama allocated funding under the 2009 stimulus to promoting the H1N1 flu vaccine.

But American conservatives for the most part have had no quarrel with vaccines – unless they are on a collision course with other deeply held beliefs, said John Evans, who teaches bioethics at the University of California at San Diego and is married to Schreiber.

“Religious conservatives are totally whole-hog with applied science, or what we call medicine,” he said. “They are all in favour of inventing new vaccines, but they have these moral lines.”

But it’s hard to discount entirely signs of growing distrust of scientists among some Republicans, even before more than 100 cases of measles were discovered in the US this year, in 14 states and Washington DC.

Climate scientists, in particular, have been accused of pursuing an ideological agenda for urging cuts to the greenhouse gas emissions that are causing global warming.

“One strand in all of this is definitely the growth within the Republican right of scepticism about scientists as authority figures,” said Theda Skocpol, professor of government and sociology at Harvard. “They just don’t accept that scientists are public authority figures.”

She also said that scepticism was growing among young people across the political spectrum – people who are not as familiar with the risks of childhood diseases because of the overall effectiveness of vaccination programmes.

Evans agreed: “It’s the Tea Party ideas of ‘don’t tread on me’ and total freedom,” he said.

Even if it carries a toll.