Is the imagery in dreams dependent upon culture and ethnicity?

In a sense yes because our dreams are reflections of things we have seen or deep inner thoughts that exist within our minds. You are constantly surrounded by some sort of culture, and that culture will appear in your dreams however ethnicity doesn't necessarily play a part. It's all about what you have seen and done during your lifetime. For example, the people in your dreams are always people you have seen before, even if in passing.

Due to the fact that we are constantly surrounded by some form of culture naturally culture will effect our dreams and cultures often vary by ethnicity so technically yes, they do both influence our dreams but only because we live our lives surrounded by culture and ethnicity.

I hope that makes sense