Hi Wutan,
McKinsey welcome all students to apply Business Analyst (BA) position, no matter what is your background.
We also had one BA like you majored in political science.
After 3 years' working, now, she is studying in Top B-school sponsered by McKinsey.
btw, GPA is the only one dimension. Leadership is also very important to us.
There will be BA recuriting campaign soon. Pls check our website.
http://www.mckinsey.com/locations/greaterchina