My two cents are boys are better performed in science subjects while girls are usually top performers in arts such as language, commerce... For the IB program which requires good time management and organizational skills, I believe that girls have a better chance of success. The Indian boy whose average was 99% last year from the IB program also said so (he mentioned that it is hard to succeed in this program without good time management skills)...
People's IQ are more or less the same... The IQ test even shows that a child could be as intelligent as Albert Einstein...