Another characteristic of first-borns, according to Frank Sulloway, author of Born to Rebel (Abacus), is caution and aversion to risk. They’re the least likely to travel or be physically daring. Again, this fits Sarah. While her middle brother took up hang-gliding and both siblings backpacked round the world, Sarah’s biggest adventure to date is a thunderstorm in France. Many theorists group only children among first-borns – although they never experience having to share their parents, nor the frictions, fights or fondness that comes with siblings. For this reason, they feel like outsiders, distanced from much of life. The only child is thought to be extremely mature, aloof, someone who expects a special standing.