Activists sometimes say "politics is in my DNA" - but there may be more truth in that than they realise. Research now suggests some of our voting habits may be hard-wired into us from birth.
When Liberal Democrat MP Matthew Taylor set out to trace his birth parents at the age of 35, nothing prepared him for what he describes as a "stunning" discovery.
Along with the news that his biological mother was alive and well and living in New Zealand with a family of her own, came another revelation - that his great-grandfather had been, like himself, a Liberal MP.
It made Mr Taylor, adopted as a newborn baby and now representing the Cornish constituency of Truro, reassess his beliefs on the eternal question of nature versus nurture.
"The fact that I followed my great-grandfather into politics is surprising enough," he says. "But the fact that I chose the same sort of politics is more than just coincidence. The odds in favour of that happening by accident must be minuscule."
Nature v nurture
Mr Taylor says that in the past he always considered that an individual's politics were determined by their environment. But he now believes that he may have inherited some of his political views from his ancestor - the East End Liberal MP Sir Percy Harris.
"If I were to guess I would say that I have inherited the characteristics of wanting to get up and argue my case," says Mr Taylor. "Also, the belief in the individual as prime and a willingness to buck the trend.
"As far as I know, these were also the characteristics of my biological great-grandfather."
Although it sounds far-fetched, there is emerging - if controversial - scientific evidence to back up Mr Taylor's claim. A study of thousands of American twins is challenging the orthodoxy that a person's experience and upbringing exclusively determine their political views.
The researchers say that how an individual reacts to social issues - whether as a radical or a conservative - is also influenced by their genes. This influence may then predispose them to vote Conservative, Labour, or Liberal Democrat.
Consistent with longstanding practices in the field of behavioural genetics, the study, by political scientists including Dr John Hibbing, from the University of Nebraska, looked at the responses given by two types of twins - identical and fraternal - to detailed questions about their political beliefs.
All the pairs of twins were assumed to have been brought up together in the same family
On the basis that the identical twins had exactly the same genetic make-up, and the fraternal (non-identical) twins shared 50% of their genes, the scientists say they were able to make a rough determinant of how genes influence social attitudes.
They calculated how often the identical twins agreed on an issue - and then subtracted the rate at which the fraternal twins agreed on the same issue.
From this, the team was able to come up with a percentage figure of how strongly the twins' views were shaped by their genes.
On the issue of "pacifism" for instance, the identical twins agreed about it at a rate of 0.34. The non-identical twins agreed at a rate of 0.15. The scientists thus calculated that on this particular issue, genetic factors contributed 38% to whether or not the twins believed in pacifism.
"It certainly made us think very deeply about politics," says Dr Hibbing. "And for those of us brought up on the conventional notions that politics are shaped entirely by class and the environment it required a big shift."
He is anxious to avoid the charge that he and his colleagues support the notion that genes exclusively pre-determine our views. "We still say that at least half of our political beliefs are still influenced by our environment."
Nonetheless, the researchers are working toward a hypothesis that how we react in certain social situations, or for example whether we have a more or less tolerant attitude towards "outsider" groups (such as immigrants) may have an underlying genetic cause.
"Much of our research is based on existing studies on personality and genetics, " said Dr Hibbing. "For instance there are certain genes that have been linked to a pre-disposition to depression."
A new quest
With that in mind scientists are setting out on a new quest - to try to identify the specific genes that may help to shape our political views.
A new team - including geneticist Dr Nicholas Martin from the Queensland Institute of Medical Research - have gone back to their twins. They are now asking more detailed questions about their politics in order to tease out what may be a more certain calculation of genetic influences on attitudes.
But in a radical new development the scientists have also decided to examine human DNA samples - in a bid to isolate genes relevant to politics. The samples have been collated by Dr Martin in Queensland from thousands of Australians who gave blood.
The team examines DNA from a database of blood samples. the "we go back and ask the person who gave the sample about their politics," says Dr Hibbing.
"What we are trying to establish is whether people who share some similar characteristics in their DNA also share a particular political trait."
The study is at a preliminary stage, and Dr Hibbing stresses that large samples are needed, and strict controls need to be put in place before the team can pronounce with confidence.
It is a controversial project however. Other scientists dispute the notion that something as abstract as a person's political preferences can be influenced by their genetic make-up.
Matthew Taylor's great-grandfather, Liberal MP Percy Harris
Geneticist Dr Dean Hamer of the US National Cancer Institute helped pioneer research that suggested the existence of genes that predispose men towards homosexuality in the 1990s.
But he is sceptical about extending the theory to embrace attitudes as well as sexual preferences.
'Memes not genes'
"Political views are memes not genes," he says - meaning that politics is more about the transmission of ideas within society, rather than an inherited characteristic.
Dr Hamer says there "might be some minor contributions from heritable personality traits but most of the variance is cultural".
Dr Hibbing admits: "We don't yet have a smoking gun linking politics and genes."
However, if he and his colleagues are proved right, the implications could be huge. Imagine a society where everyone's DNA "map" was available. Corporations and political parties with access to the right information might be able to target specific individuals - knowing that they might be genetically predisposed to being sympathetic to a particular party's propaganda.
Matthew Taylor was one of the youngest MPs ever elected
And from an existential point of view, how would we feel if it was proven that at least some of the element of choice had been removed from our political affiliations? Would we feel like prisoners of our own DNA?
As far as Dr Hibbing is concerned however, the possibility of genetic political influences might lead to more political tolerance.
"If people accept that others have different political views, not because they are bull-headed, but because they are predisposed to believe those things then I am hoping that will take a lot of rancour out of politics.
A healthy political mix
"And it may turn out that since the dawn of human history, successful groups have naturally had a healthy mixture of radicals and conservatives. Which is a good thing for us all to know."
As far as MP Matthew Taylor is concerned however, he does not need convincing.
He now watches his own two young sons with different eyes.
"My eldest - Arthur - is only 15 months old," says Mr Taylor, "but he is empathetic; he likes to stand and watch. He is naturally shy, but will make himself join in. As a young MP - that was me."
Below is a selection of your comments.
A persons Genes does not MAKE a person be or do anything. People do what they do from choice, a person's character is the sum of those choices.
Genetics seems to me to be a means of removing the idea of personal responsibility.
David Rawson, Nottingham
What is the big deal? Anyone who breds and works with performance animals (typically dogs and horses) will tell you that temperment and attitude can be predicted based upon the ancestors. I've a lovely 4 year old Kuvasz - a breed supposedly "aloof, standoffish and guardy with strangers". This dog has never met anyone he doesn't like - everyone is a potential friend. I picked my young dog based upon the family traits of being able to learn various demanding tasks and happily cope with chaotic situations and crowds of strangers, while remaining relaxed and outgoing. He is now one of three dogs in his breed to be a Service Dog (or Assistance Partner), which is an immensely challenging job requiring certain personality traits and attitudes. So again, what is the big deal? Last I heard humans are mammals too and behavior is affected by neurolgical biochemistry which is controlled by genes.
Ann, Traverse City, MI, US
Utter tosh. So he votes the same way as his great-grandfather, so what? Most of us have four great-grandfathers, does he vote the same way as all of them? Did his grandfathers and father vote the same way? How about his mother? Going into politics could well have been influenced by a story about his ancestor, and the choice of party is at worst a one in three chance that it would be the same one, that's a very long way from "miniscule". There may indeed be some genetic bias which could influence choice of political party, but not on an actual party level. Some people do seem to be predisposed to peace or violence, to accepting authority or wanting to exert authority, but there is so much environmental influence that it is very hard to tell. Twins aren't necessarily brought up identically, all of the pairs of identical twins I've known have had quite divergent feelings on some subjects, particularly emotional ones such as politics.
Chris C, Aylesbury UK
I was adopted at birth. Four years ago (I'm now 47), I traced my natural parents, both of whom have new families. To my amazement, I seem to have a great deal in common with both parents - my drawing ability and love of books from my mother, my political and ethical views from my father. In addition, I also have a great deal in common with my half-brothers, even to the extent that they had some of the same books on their shelves as I did. It certainly changed my views on the Nature Vs Nurture debate.
Rob, London, UK
What a load of absolute rubbish. Sounds like a way of justifying political views to me, and if you're not able to do that without pointing to your genetic makeup then perhaps you shouldn't be in politics. Couldn't the close bond between identical twins be as much to do with enviromental reasons as genetics anyway? I don't know about you but sharing a womb for nine months with someone sounds like an enviroment to me.
John Graham, Basingstoke
Most interesting - but I would not attach too much weight to either side of the nature vs. nurture debate. After all, the question of political preferences is complex; surely it is not a matter of genetics alone - although a tendency to see the world in a certain way, in the broadest possible sense of the phrase, could well have genetic roots. Obviously patterns of behaviour are learned, but the tendencies towards them and the very fact that these are potentially at hand are genetically determined. Nature provides the potential (and we may find that some potential is provided in astonishing detail), nurture determines whether the potential can also become reality (and we find some surprises here too).
D. Fear, Heidelberg, Germany
My family would suggest there is no link between voting preferences and genetics. My grandmother was an ardent Thatcherite and Tory councillor. My mum, her daughter-in-law, was an active Conservative Party member too. Of my four siblings, I vote Labour, one sister has left-wing leanings and the other two profess to be uninterested in politics, possibly scarred for life by having the watch the Tory party conference on TV at Nan's for years!
Heckles, Wiltshire, UK
I've been convinced for many years that can you inherit an ancestor's "living memory" through your DNA and that it can also trigger a "life choice".My son for example was mad on submarines and the sea when a toddler in the 70's yet we lived in the Midlands, miles from ships or any coast. He read book after book on the subject and just had to have 'Das Boot' when it came out on DVD in the 80's, an odd choice for a small child. In the past few years I've been researching my family tree and have discovered that his great grandfather [a Manchester man] worked on the very first submarines at Barrow in Furness. He was apprenticed there and actually went out to sea in a submarine in 1903.
I know that's more than coincidence !
"But the fact that I chose the same sort of politics is more than just coincidence. The odds in favour of that happening by accident must be minuscule." Yet another person who has difficulty with statistics. If there are only two, three or four political parties, there's nothing remarkable that any one of them happens to be chosen. "If I were to guess I would say that I have inherited the characteristics of wanting to get up and argue my case," says Mr Taylor. Guessing is all he seems to do!
Lambert Heenan, New York, NY USA
I met my father when I was 40 and found out that his parents had been Labour Mayor and Mayoress of Finsbury in London. At the time I was a Labour Councillor in the Frindsbury Ward on Rochester Council.
Chris Fribbins, Rochester, Kent
Very Sceptical about this one, George Monbiot the radical Green and Leftist's father is an active Conservative.
The odds of both men being Lib Dems are truly miniscule!