Being a sibling is a fight for survival

http://www.theguardian.com/lifeandstyle/2015/may/22/being-a-sibling-is-a-fight-for-survival

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As regular readers of this column will know, I have four daughters, each of whom I consider to be remarkable in her own way. Perhaps the most remarkable thing about them, however, is that they are all completely different from one another.

What’s so odd about that? Actually, when you think about it, wherever you stand on the nature/nurture debate, it is quite unexpected. Obviously the two from my first marriage are likely to be different to the two from my second marriage, as they had different environments and a different genetic mix. However, each pair that grew up in the same household and who share half their genetic inheritance from their parents, had a very similar environment. But as far as I can make out, there is little to connect them. In fact they are more different than I would expect two strangers to be.

Psychologists, on the whole, broadly believe that one’s fundamental personality traits – openness, conscientiousness, extraversion, agreeableness and neuroticism – are determined half by genetic inheritance and half by environmental factors. This should mean that my daughters, each “pair” of them, should at least be more broadly similar than a random sample. But as far as I can see – admittedly without running any formal psychological profiles – they are not.

How can this be? One solution was offered to me when I was researching my novel on sibling rivalry, Under the Same Stars. Interviewing various developmental psychologists, I came across the idea that siblings make a deliberate and conscious effort not to be like their siblings in order to establish themselves as individuals.

Being a sibling is a fight for survival. As the psychologist Dorothy Rowe, author of My Dearest Enemy, My Dangerous Friend: Making and Breaking Sibling Bonds writes: “Siblings may scream insults at one another, or exchange heavy blows, or destroy each other’s possessions. Such fights are bitter and vicious, necessarily so because each sibling is fighting for survival as a person.”

One of the aspects this battle takes on is described by Judy Dunn, author of Separate Lives: Why Siblings are so Different: “You work out quite early on what aspects of your [sibling’s] personality makes him (or her) a success and you make yourself as different as possible [my italics]. The more time [siblings] spend in the same family, the more different they get. Even with identical twins, the longer they live in the same family, the more different they become. You try and secure your own identity not by emulating a sibling, but by reacting against them. You become an individual by not being your brother or sister.”

This supports my idea that when trying to understand the behaviour of children – or adults for that matter – one has to go beyond environment and heredity. What makes people different from one another is interpretation – the stories we tell ourselves about our experiences and the way we defend our identities against threat.

This matter of interpretation is not determined in any genetic or environmental sense. We are, to some extent, free to make sense of the world we are presented with in the way that we choose – even though, as a child, our information is limited and our interpretations immature. Thus we may often choose a bad or maladaptive way of making sense – hence the need for therapy later in life and the outcomes of depression, for instance. But it is still a choice.

The good news about this is that your children are different because they are free to be different, and they desire to be different. The person we invent out of our genetic personality, our upbringing and the meanings we construct is unique. And that is why when your children fight they are not just fighting to secure a privilege or win an argument. They are fighting to determine who they will become.

• @timlottwriter