Individual things that make us, us

The sentence is complete. The topic is how they came to become the people they now are (makes us “us”).

Third culture kids (TCK) are people from one culture who go to live in another culture for a long time. In the process, they lose parts of their original culture but don’t quite assimilate fully into the other. As you might imagine, this can have quite an impact on who they become.

The TCK is asking about how they became who they now are, and in particular, what specific things were formative in this process. For example, they might have left all their friends in America and had to make new friends in Japan who speak a language the TCK wasn’t yet fluent in. This could have led to them developing a knack for quickly reading body language to find the most welcoming people. In that case, having to communicate non-verbally helped make them, them.