To suggest that Wyndham does indeed "evoke different feelings" in different readers through any given aspect of his character portrayals assumes, on the one hand, that the critical approach of Reader Response is a correct one, while, on the other hand, it also assumes that parent-child relationships are so complex that it is reasonable to suppose different feelings are evoked.
Since it is true that parent-child relationships are indeed complexly multi-dimensional and multi-problematic, it is reasonable to attempt to answer this question from an objective point of view and say that, without research to verify the actuality of the assumption, it is reasonable that readers may have differing feelings evoked and, further, different kinds of parents may have differing feelings evoked.
How does Wyndham do this? One way he does this is to present incidents with multiple perspectives. This is not to say there are multiple points of view: there is one point of view and that is David's first-person narrator point of view. The incident in which David is asked to reveal Sophie's name is a good illustration of the multi-perspective approach Wyndham takes that may evoke differing feelings in different readers.
'I'll deal with this. The boy's lying.' To me he added: 'Go to your room.'
I hesitated. I knew well enough what that meant, but I knew, too, that with my father in his present mood it would happen whether I told or not. I set my jaw, and turned to go. My father followed, picking up a whip from the table as he came.
'That,' said the inspector curtly, 'is my whip.'
My father seemed not to hear him. The inspector stood up. 'I said that is my whip,' he repeated, with a hard, ominous note in his voice.
My father checked his step. With an ill-tempered gesture he threw the whip back on the table. He glared at the inspector, and then turned to follow me.
In this incident, three perspectives are presented; these are David's perspective, the Inspector's perspective, and David's father's, Joseph Strorm's, perspective. From David's perspective we see a young man acting ethically and morally in a cultural situation that requires ruthless betrayal based on a cultural assumption and resultant legal requirement. This may evoke feelings of anxiety, approval, admiration, sympathy (not empathy) or feelings of reproach, disapproval, shame, rejection for some readers.
From the Inspector's perspective we see two things. We see his kindly regard for David's age and situation, despite his dedication to his authoritarian role and legal obligations (and commitment). We also see his stern, almost hostile reaction the Joseph Strorm when Strorm silently reveals his intentions for dealing with David. This may evoke feelings of censure or appreciation, fear or approval, admiration or distain for different readers.
From Strorm's perspective we see a cold, heartless, demand for compliance with legal and cultural demands with no mitigating appreciation of personal circumstances or feelings [this contrasts with the Inspector's mitigating approach (mitigate: to lessen the gravity, severity, or painfulness of something)]. This may evoke either feelings of approval or disapproval, rage or sympathy, repulsion or favor for different readers.
Thus, readers may associate particularly with one or the other of the perspectives and with one or the other other kinds of reactions. Thus variableness in association and reaction may evoke differing feelings in different readers. It can be argued, though, that Wyndham would have intended that all readers share similar emotional reactions, those being sympathy with David, approval of the Inspector's ire at Strorm, and repelling disapproval of Strorm.