How did Obama’s personal story help to shape his trajectory towards the presidency?

Barack Obama's memoir Dreams from My Father: A Story of Race and Inheritance was published in 1995, years before he was elected into the Senate (and later, into the presidency). The story he tells in this book covers his childhood, adolescence, and early adulthood, and features several key events that paved his way toward becoming the US President in 2008.
Let's go over each of these key events.
First up: early independence. Obama's parents separated when he was two, and his father was largely absent in his life. With his mother and stepfather, Obama moved from Hawaii to Jakarta. But at the age of ten, he moved back to Hawaii to attend a private high school. Initially, back in Hawaii, he was cared for by his grandparents. In other words, he never had two stable parents taking care of him; he adapted to a variety of situations, even as a child.
Admission into that private high school, Punahou Academy, was key to Obama's academic growth, as well as to his identity as a young black man. At the school, he meets a friend who's a few years older, and who, like Obama, is biracial. This friendship, and Obama's subsequent entry into an African-American community, would prove crucial to his self-image and understanding of race relations as a politician.
Obama's success in a prestigious high school helped him to gain entry into college in Los Angeles, though he ultimately transfers to Columbia. There, he majors in political science, starting to build a framework for what would become a political career.
One more key event is important in the shaping of Obama's future career. One is the fact that he moved to Chicago after graduating from university, where he took a job as a community organizer. In this demanding role, Obama learned a lot about what it is to work with groups that don't share the same goals or values, which would prove important for his later role as president.