why

While doing my internship at Stedelijk Museum Schiedam at the education department I came to the conclusion that the museum, literally and figuratively, is a white cube.
Almost the whole staff of the museum was white and around fourty years old. But it was not just the people who worked there, also most of the visitors were white. This is what I find problematic.
Museums represent themselves as an institution that is open to/for everyone, but why can't we see that? Why is still the biggest part of the visitors white?
Is it about the way the museum represent itself?
Is it about the way the museum represent other cultures? (with other cultures I mean all the cultures except for the dominant white European culture we see in museums)
Is it about the curriculum and the things we learn in (art)history?
Or is it about the fact that we are still ashamed or don't want to admit for the things that happend in the past. (colonization) Are we hiding the past behind art?

My father was born in Papua New Guinea (Manokwari, West-Papua). When he was born it was still called Nederlands Nieuw Guinea. My grandparents moved to New Guinea for my grandfather's work. I don't know a lot about their time there. I only know the stories of my grandmother. She told some stories about their life there (she didn't worked and took care of the kids). According to that they had a good life there. The few stories I know are mostly about animals. Crocodiles in the kitchen and snakes on the windows. My father doesn't remember a lot about his time there. His most clear memory is eating big bugs he found in the garden. I don't know the stories of my grandfather, he passed away before I was born. I think his stories are the most important ones. Why did they moved there? What was his job? What was his relationship with the Papuan people?
When Papua New Guinea got their independence my father and his family had to move back to the Netherlands.
Back at my parent's and grandmother's place are a lot of objects (drums, masks, dolls) of Papua New Guinea. Sometimes I wonder how those things got here? Did they got it as a gift or was it stolen?