1. A system comprising: a processor configured to initiate executable operations comprising: identifying a class inheritance structure for at least one parent class contained in computer program code to determine a class hierarchy corresponding to the parent class; for at least one child class in the class hierarchy that is a child of the parent class, calculating a parent-child similarity value corresponding to a parent-child diversion of the child class from the parent class, the parent-child similarity value comprising at least one numeral; based on the parent-child similarity value corresponding to the parent-child diversion of the child class from the parent class and parent-child similarity values of other children of the parent class, determining standard deviation for the parent-child similarity value corresponding to the parent-child diversion of the child class from the parent class; generating, by the processor, the class diagram, the class diagram indicating at least the parent class, the child class, the parent-child similarity value, and the standard deviation; and presenting the class diagram.