She could be withdrawn or paranoid, but she was also funny, sarcastic and a little bit wild I liked to imagine I took after her. She had a degree in modern languages and before becoming ill led a romantic life in wartime London. As a teenager I wore the stylish clothes I found put away in a trunk full of her possessions from that time and read the novels inscribed to her in elegant script by her Polish lover. When I studied German at school, she - who now had almost no short-term memory - took real pleasure in quoting by heart Heine and Goethe. My mother had disliked being a twin and grew up defining herself in opposition to her sister. She always saw Margaret as the clever, artistic one and herself as the sporty duffer. As a well-travelled adult, her first thought when she arrived in any magical location was that it should have been Margaret there to enjoy it, not her. But they were alike in other ways: my brave, loving mother sometimes suffered from the same paranoid sense of persecution as her sister. I learnt early how to navigate around her social anxieties and delusions, but they were never to be described in medical terms. The hospitals where Auntie Mardie lived were early-19th-century asylums, imposing red-brick edifices set in salubrious grounds. New clothes or money went missing. Sometimes there were issues of inadequate care or incorrect medication. Some days Margaret was better than others. While my mother sorted things out, I waited in the car, an object of curiosity to the bored patients who would stand and stare or even peer inside. Sometimes Auntie Mardie sat with me and confided which doctor was in love with her this week. Once, when I was nine, soon after my grandmother had died, she whispered about the secret letters she'd received from her mother saying she wasn't really dead. No terrible secrecy surrounded my aunt, yet the visits were - in my hearing at least - never discussed between my parents, and no one ever asked if I was OK or minded witnessing how distressed my mother sometimes became. Years later my mother worried that it was wrong to have involved me as much as she did, that my aunt had been a burden to me. It never occurred to me to see Auntie Mardie that way; the unshared burden was my mother's grief. I am the only member of my family without a medical degree, yet from a very young age I was expected, in being my mother's companion and keeping her anxieties in check, to assume the mantle of dispassionate responsibility and discretion that went (in my parents" eyes) with 'being medical." But, because of her understandable refusal to be a patient, barricaded behind the talismanic white coat and stethoscope, it was never possible to offer her a cure for how wounded she'd been by Margaret's illness. Being medical" meant being a survivor, not a victim. It wasn't healthy. The Bad Mother," by Isabelle Grey, is published by Quercus at £7.99