What logical fallacy is being used if it is argued that because a person has a relative who was good, they must also be good?

The argument in question exemplifies the Division fallacy. This fallacy occurs when it is incorrectly assumed that what is true of a whole must also be true of its parts. In this scenario, the reasoning assumes that because a relative of the individual is considered good, it follows that the individual must also possess the same qualities. This reasoning fails to recognize that individuals can have different attributes regardless of their familial connections or relationships.

While the conclusion drawn may seem plausible to some, it overlooks the complexity of individual character and behavior. Each person has unique experiences and choices that shape who they are, independent of their relatives' qualities. Thus, an individual cannot be deemed good or bad solely based on the actions or characteristics of their family members. Recognizing this fallacy helps in critically assessing claims about individuals based on their associations.