What early indications suggest why Laurie has behaved so badly at school in "Charles" by Shirley Jackson?

The bad behavior of Laurie in the exposition of the story "Charles" foreshadows the way in which he will conduct himself at school. For, it is apparent that he is undisciplined.
Laurie's willfulness and disrespect is suggested in the verbs renounced and swaggered when the mother narrates that the boy decides on his own to dress in blue jeans and a belt rather than his usual overalls with bibs. Then, too, he walks with an older girl to school without even waving good-by to his mother. After the school day is finished, Laurie returns home in "the same way" that he has departed. He lets the door slam behind him and in a "raucous" voice Laurie shouts, "Isn't anybody here?"While the family has lunch, Laurie speaks "insolently to his father" and he knocks over his baby sister's milk. He tells his parents "not to take the name of the Lord in vain." This statement, of course, indicates that Laurie must have cursed and then excused himself to the teacher by saying that his parents do this at home.
It is quite apparent that Laurie's parents are permissive as the mother describes his behavior without mentioning any discipline having been given to her boy. For instance, she has not called to him to wave good-by, nor does she later scold him for slamming the door, or for  spilling his sister's milk, as well as for speaking in an insolent tone. Also, she does not ask him what words he has used at school to have caused the teacher to say that his parents must not use the name of the Lord.Further, Laurie casually mentions "with his mouth full" that the teacher spanked "a boy" for "being fresh." When his father asks him what this boy has done, Laurie ignores the question; instead, he takes a cookie, and slides off his chair without his father's reprimanding him for not answering.