Extend the following article from pure likes and dislikes into racial preferences and we see the built in mechanism that nature has supplied us with to keep to keep the different races and species separate and pure. Taking it one step further, our Love and Hate instincts are built into our DNA. Unless you are born as an abomination of nature, you are born heterosexual and racist. It's pure genetics.
@Cailen.Gene magnetism Nicky Phillips March 10, 2011
http://www.smh.com.au/world/science/gene-magnetism-20110309-1bnun.html (http://www.smh.com.au/world/science/gene-magnetism-20110309-1bnun.html)
Your chances of being drawn to or repelled by someone may be determined by your DNA, writes Nicky Phillips.
Have you ever met someone you instantly disliked?
By most measures the two of you should have been great friends: you may have lived in the same suburb, known the same people, or even shared a love of some obscure 1970s punk-rock band.
But for some inexplicable reason, after knowing them for less than half an hour, you could not stand the sight of them.
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The reason for such disdain - or the opposite effect, where you instantly click with someone - could lie in your genes.
The idea that friendship may have a genetic basis came to a geneticist at the University of California, San Diego, Professor James Fowler, after he wrote a book on the power of social networks.
He already knew that friend networks influenced a person's health. If your best mate becomes obese it increases your chance of becoming obese by 57 per cent.
But could the way humans naturally form clans, partnerships, teams and even gangs be, in part, written in our biology?
An intriguing clue emerged when he found identical twins have more closely connected friend networks than non-identical twins.
To Fowler this was the first sign that friends not only share likes and dislikes but could resemble each other on a genetic level.
''This was a step towards understanding the science of human chemistry - the idea that you might click with somebody as a consequence of biological similarities or differences,'' he says.
Fowler and his colleagues used data from two long-running epidemiological studies to compare the likelihood that friends shared similar genomes.
The group looked at the gene DRD2, which has been linked to alcoholism, and found friends were more likely to have the same version of the gene.
This positive correlation makes sense when you think about it, says Fowler, a professor of medical genetics.
''Suppose you are choosing other people to drink with. You don't want to hang out with teetotallers so you select friends who are like you,'' he says.
But Fowler could not be sure these people were choosing their friends based on a subtle influence of their genes or if they just happened to drink at the same place, at the same time.
''With positive correlation we can't rule out one of those two possibilities,'' says Fowler, who has the version of the DRD2 gene linked to alcoholism.
When the group studied another gene, CYP2A6, which some studies have shown is linked to openness, they found the opposite effect. People who had one version of the gene were more likely to be friends with people who had the opposite genotype.
In this case, Fowler could rule out the environmental influence.
It is not going to be the case that a person with one version of the genotype and their friend with a different version of the genotype are going to be drawn to the same environment, he says.
''For that outcome it is more likely it is a consequence of friendship choice.''
The group compared another four genes. Three had no association and one appeared to have a slight correlation among friends.
While the result appears to be small, it is significant.
He expects further studies that look at the entire genome will uncover dozens, possibly hundreds, of other markers that show signs of correlation among friends.
The results are also supported by Fowler's earlier research that found identical twins had more similar social networks than fraternal twins.
This showed that genes play a role in influencing how many friends you have and even if two of your friends are friends with one another.
''Genes affect how social we are and how likely we are to try to introduce our friends,'' says Fowler, whose findings were published in the Proceedings of the National Academy of Sciences.
The friends we get introduced to can have a bigger effect on our biology than many people realise.
For a start, your friends can make you overweight. And not just your own friends but your friends' friends' friends.
Fowler and a long-term colleague, Nicholas Christakis, made this finding when they started to investigate whether social networks could influence certain health conditions.
From detailed data held by the Framingham Heart Study, an epidemiological study that has followed a group of people, their friends and their families for more than 50 years, the pair found obesity spreads by up to three degrees of separation.
''So if your friend is obese then it increases the likelihood that you will be obese by about 40 per cent. If your friend's friend is obese it increases your likelihood of being obese by 20 per cent. And if your friend's friend's friend is obese it increases your chance by 10 per cent,'' Fowler says.
He gives two possible explanations for why overweight friends seem to cluster together. It could be that people are choosing to be friends with people who are like them.
''Normal-weight people are choosing other normal-weight people to be friends with,'' he says.
Or it could be that friends are exposed to similar environments.
''So if a gym opens up down the street from you and your best friend, you may not even talk about it but each of you independently join the gym and you both lose some weight, so it looks like your weight is going up and down together when really you just live in the same environment,'' he says.
But what Fowler and Christakis, a professor of medicine at Harvard University, really wanted to know was if the obesity epidemic could be an epidemic that spreads from person to person like the flu does.
They went back to the Framingham Heart Study data.
With records collected for more than 30 years, they were able to model how people form friendships in the first place.
They used this to determine a person's risk of becoming obese if their friend does.
''If the person you named as a friend became obese, it increased the chance that you would become obese in the next two to four years by 57 per cent,'' Fowler says.
The finding shocked the researchers who then decided to reverse the situation. If a person named you as a friend but you didn't name them would their weight have an influence on yours?
Apparently not.
A person is only influenced by the weight of someone they consider a friend.
''Now we have evidence that this isn't about the gym opening up down the street from the two of you, because if that was the case then you should be just as affected by the people who name you as a friend as you are by the people you name as a friend,'' Fowler says.
''There is directionality. [Obesity] is spreading from one person to another.''
Fowler admits there could be other explanations for this phenomenon.
''But for these really important health behaviours it really is a story of birds of a feather flock together,'' he says.
And now that Fowler has found genes are linked among friends he would not be surprised if certain genes known to influence obesity are also shared among mates.
From an evolutionary perspective, there are several advantages for friends to share similar or complementary genotypes.
If genes are anything like new technology, then mass adoption is key.
''If you are the only person in the world with a fax it is going to do you no good, but if your friend has one you can use it,'' he says.
The utility of the fax machine grows exponentially with an increasing uptake. Perhaps genes work in a similar way.
For example, if an early human developed a genetic mutation that suddenly allowed them to speak or understand language it would be of no use if other people didn't have the same genotype.
''Things that we attribute to environmental influences might instead be genetic influences,'' he says.
The idea that friendships have a biological basis has been around for some time. The British anthropologist Robin Dunbar says humans have larger brains primarily to deal with living in larger groups, a trend that developed in our primate ancestors.
For them, living with others provided protection.
But it meant the species had to develop the mental capacity to keep track of multiple individuals.
As a result, human beings can not only understand the direct relationships they have with other people but the relationships those people have with one another.
''When you are making decisions about what to do with Jane, in part you also have to think about what Jane's relationship is with Sally,'' Fowler says.
Anyone that's lived and worked around them are gonna hate them. Comes natural.88