When the Wharton School enrolled its latest MBA cohort consisting of 52% women, there was celebration all around. But it turns out that Wharton, having reached gender parity, has been outdone in both the U.S. and abroad. The U.S. leader is George Washington University's business school where 57% of the latest cohort is female. Worldwide, the top MBA class may well have the reverse problem: Some 77% of the newest MBA class at Tongji University is female.