I don’t think it is so much that your 20s define who you are, it is that they reveal who we are. Genetics is most important. The people I know who are most successful today did well in their 20s, but they also did well as children and in their teens. They have good genes, they come from families where their parents did well in life, and made good choices. People with athletic parents tend to be athletic, people from musical parents tend to be musical, people with good looking parents tend to be good looking, people with smart parents tend to be smart, people with disciplined parents tend to be disciplined, people with sociable friendly parents tend to be social and friendly. people whose parents divorced, are more likely to divorce, people with parents who are alcoholics or addicts are more likely to be addicts. As a psychologist and author, Meg Jay is going to be predisposed to thinking that if people take her advice, they’re going to succeed… Perhaps people with good genes have less need of her advice, and people with bad genes are going to have less ability to follow good advice.