After my parents split up, my older sister and I lived with our dad while the youngest stayed with our mum. It became an experiment in nature v nurture - and had a profound effect on our relationships

There is a paradox at the heart of sibling relationships and it is this: that children raised in the same family are for ever bound by shared experiences, yet have different childhoods. The paradox is partly (and most commonly) explained by the topic of birth order theory – the idea that your position in the family shapes your personality and potential. Oldest children, for example, are born into an adult world, full of grown-up language and behaviour. Governed by anxious, inexperienced but still fresh parents, they bask in the glow of undivided attention. Their infancy will be markedly different to that of their little brother or sister who will be born into a family . These second-born children have a toddler as their role model/ally/nemesis, no new clothes, and they also have to share their parents’ attention. These parents are a little less fresh and little more savvy. By the time any subsequent children come along, parents are at their most relaxed and most exhausted. Youngest children get away with a lot (spoken as a true middle sibling).

But neat as birth order theory may be, our place in the family roll call cannot fully account for the ways in which we grow up “together apart” as siblings. To do that, we must examine – and in some cases untangle – all of the knottiness underpinning our accepted roles as “responsible firstborns”, “problematic middles” or “spoilt babies”. We need to look at the home environment, the state of the parents’ relationship, their careers, the pressures placed on each child on account of gender or aptitude, the expectations in families where a child has additional needs – or indeed, in the worst-case scenario, where a child may not have survived – before we can begin to comprehend our brother’s or sister’s version of events. Difficulties typically arise because of the slipperiness of memory, often shot through with profound emotions – making it hard to pull together a coherent and agreed-upon story of our pasts.

After my parents split up, my older sister and I lived with our dad while the youngest stayed with our mum. It became an experiment in nature v nurture - and had a profound effect on our relationships

There is a paradox at the heart of sibling relationships and it is this: that children raised in the same family are for ever bound by shared experiences, yet have different childhoods. The paradox is partly (and most commonly) explained by the topic of birth order theory – the idea that your position in the family shapes your personality and potential. Oldest children, for example, are born into an adult world, full of grown-up language and behaviour. Governed by anxious, inexperienced but still fresh parents, they bask in the glow of undivided attention. Their infancy will be markedly different to that of their little brother or sister who will be born into a family . These second-born children have a toddler as their role model/ally/nemesis, no new clothes, and they also have to share their parents’ attention. These parents are a little less fresh and little more savvy. By the time any subsequent children come along, parents are at their most relaxed and most exhausted. Youngest children get away with a lot (spoken as a true middle sibling).

But neat as birth order theory may be, our place in the family roll call cannot fully account for the ways in which we grow up “together apart” as siblings. To do that, we must examine – and in some cases untangle – all of the knottiness underpinning our accepted roles as “responsible firstborns”, “problematic middles” or “spoilt babies”. We need to look at the home environment, the state of the parents’ relationship, their careers, the pressures placed on each child on account of gender or aptitude, the expectations in families where a child has additional needs – or indeed, in the worst-case scenario, where a child may not have survived – before we can begin to comprehend our brother’s or sister’s version of events. Difficulties typically arise because of the slipperiness of memory, often shot through with profound emotions – making it hard to pull together a coherent and agreed-upon story of our pasts.

After my parents split up, my older sister and I lived with our dad while the youngest stayed with our mum. It became an experiment in nature v nurture - and had a profound effect on our relationships

There is a paradox at the heart of sibling relationships and it is this: that children raised in the same family are for ever bound by shared experiences, yet have different childhoods. The paradox is partly (and most commonly) explained by the topic of birth order theory – the idea that your position in the family shapes your personality and potential. Oldest children, for example, are born into an adult world, full of grown-up language and behaviour. Governed by anxious, inexperienced but still fresh parents, they bask in the glow of undivided attention. Their infancy will be markedly different to that of their little brother or sister who will be born into a family . These second-born children have a toddler as their role model/ally/nemesis, no new clothes, and they also have to share their parents’ attention. These parents are a little less fresh and little more savvy. By the time any subsequent children come along, parents are at their most relaxed and most exhausted. Youngest children get away with a lot (spoken as a true middle sibling).

But neat as birth order theory may be, our place in the family roll call cannot fully account for the ways in which we grow up “together apart” as siblings. To do that, we must examine – and in some cases untangle – all of the knottiness underpinning our accepted roles as “responsible firstborns”, “problematic middles” or “spoilt babies”. We need to look at the home environment, the state of the parents’ relationship, their careers, the pressures placed on each child on account of gender or aptitude, the expectations in families where a child has additional needs – or indeed, in the worst-case scenario, where a child may not have survived – before we can begin to comprehend our brother’s or sister’s version of events. Difficulties typically arise because of the slipperiness of memory, often shot through with profound emotions – making it hard to pull together a coherent and agreed-upon story of our pasts.