What gave Bigger's mother an insight to the kind of company Bigger keeps

The opening section of Native Son, titled "Fear," is as much focused on the conflicts within the Thomas family as on the poverty in which they live. Bigger's mother is aware of the "gang" he pals around with and blames them, partly, for Bigger's refusal to take jobs offered to him and for his disrespectful behavior to her and his sister, whom he taunts with the body of the rat he kills. Yet Bigger himself doesn't really like his friends Gus and G.H., and Mrs. Thomas is mistaken that they are the ones causing Bigger to behave irresponsibly and rebelliously. They're only a sideshow, a result of the overall problem and not the source.
Mrs. Thomas is correct that Bigger's "delinquency" is caused by influences outside his immediate home life, which is dire in itself but beyond her ability to change. It is understandable that she would attribute this to those with whom he associates outside the family. But Bigger's insight into his situation extends beyond what his family can imagine he is aware of. He perceives the injustice of the racist system of the time and the corruption of the white leaders, such as the State's Attorney candidate Buckley whose posters are plastered on the neighborhood walls. He articulates inwardly the reason for his anger, but says little to others beyond what is already obvious to them. Still, Bigger has no social mechanism available by which he can fight the system. The job with the Daltons would have made his mother happy, solved their money problems and freed him from the "gang" through which he would have landed in more trouble, yet Bigger finds his status as a servant intolerable, especially after Jan and Mary, through their ignorance, treat him with insensitivity and condescension. The murder of Mary, though partly accidental, represents an outpouring of Bigger's aggression which he had previously expressed in petty robberies with his friends. His mother, in having been mistaken that the friends had caused Bigger's problems, was thus also mistaken or in denial as to the root of Bigger'a anti-social behavior, and the severity of its consequences.