From the genetic point of view two very casual encounters are at the heart of our personality. The first concerns how mum and dad met and the second is how a particular sperm cell met a particular egg each having a casual assembly of half of the genome of each parent. The interactions of mixtures of the two genomes strongly influence our personality. They give rise to cerebral circuits programed to collect experiences from the social and physical world surrounding us. Here too the cultural, social, religious economic, geographical and economical world around us is a turn of the roulette wheel. Furthermore, the number and type of siblings, teachers, friends with whom we spend hours and hours a day are decided by chance. Our cerebral circuits waiting to be programed by these situations, all so different, will wake up in specific moments which are critical for our development. For example, we learn the tone and accent of our mother tongue in a specific moment of our life; we prefer the company of our friends to that of our parents when we are adolescents and not when we are two years old. Clearly, the number of chance genetic and environmental events we are exposed to is enormous and we have no say on the critical periods. So, when we consider the particular personality of somebody we know, we must have compassion and understanding and realize the role played by absolute chance in how this personality was shaped.