Final answer:
All four students discovered that they were from wealthy families.
Step-by-step explanation:
Ruth and Kit discovered that all four students had in common that they were from wealthy families. In the study conducted by sociologist Annette Lareau, it was found that parents from higher-income families actively fostered and accessed their child's talents, opinions, and skills, and introduced them to a wide range of activities. This emphasis on wealth and access to opportunities indicates that the students were from wealthy families.