What's on your music player? If you're older than 30 years, it probably includes songs from your teenage years. Childhood and adolescence are the most impressionable period of a person's life. The earliest memories and experiences are essential in shaping character—and they profoundly influence everything that comes next. “The habits we form from childhood make no small difference, but rather they make all the difference,” Aristotle proclaimed more than 2,000 years ago.