Answer:
Jen claims that our culture doesn't fully define us - there are many other factors that make us who we are today, including our upbringing, history, psyche, surroundings, etc.
She is talking about Asian-Americans and how differently they raise their children now than they used to in the past. Although there are still 'stereotypical' Asian parents who want their children to become doctors and scientists, there are also those who support their children's dreams of becoming athletes and following another path than the one their parents set for them. She talks about Jeremy Lin on one hand, and her brother Bob on another - Lin's parents supported his athletic career wholeheartedly whereas her parents wanted Bob to become a doctor, despite his obvious athletic skills in lacrosse.
Even though both families come from the same or similar cultures, one son was allowed to become who he truly wanted to be whereas the other one had very stereotypical Asian expectations from his parents.
