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 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 T here is a paradox at the heart of sibling relationships and it is this: that children raised in