parent child
Chris Nolan’s movies often explore the parent relationship with the kids. Batman loses his dad and is defined by loss. Dom in inception just has to do one last job to make it back to his kids. Cooper in interstellar is torn by trying to save his kids or spend time with them. Tenet - lady goes through hell just to see her boy.
Perhaps his fascination by this relationship because it is the more important one in our life. It defines us more than anything else. It shapes our identity. Our habits. Our looks. Our dreams. The way we feel love. How we think. Even what foods we like. All can be traced back in some way to the parents.
This isn’t always “my parent did X so I did X.” Often the inverse is true, because my parent did X, I did Y.