Everyone's upbringing was different, as everyone's life is totally unique. That being said, those of similar social circles can share some overarching experiences and themes in their upbringing that allow them to relate to each other later on.
That's the phenomenon experienced in a Reddit thread where people who grew up poor were asked to share things they associate with wealth.
For every answer, there were leagues of replies from other people who grew up poor saying they felt the same way.