what actions of charles wallace's indicate the he has a "sixth sense" when it comes to meg

Charles Wallace tells her that he had been expecting her (at breakfast), and Meg wonders how he could “always know about her” and how he could probe her and her mother’s mind with “frightening accuracy.”

"Too windy up in that attic of yours," the little boy said. "I knew you'd be down. I put some milk on the stove for you. It ought to be hot by now."

How did Charles Wallace always know about her? How could he always tell? He never knew — or seemed to care — what Dennys or Sandy were thinking.