What does it mean when Charles Wallace says that Meg is not like him and Calvin?

Charles
Wallace and Meg run into Calvin in the
woods near Mrs. Whatsit's house as they are on the way to
visit her. Charles
Wallace is highly suspicious of what Calvin is doing there. He doesn't know

Calvin, and he questions him about why he is walking in this particular
spot.

Calvin finally explains that he came because he had
a "compulsion" to be
there. It was gut feeling, an intuitive knowing.
Charles...