Japan shin...the two go hand in hand.
The ideals of a culture can often be found in their art work and literature. True there will always be extremes, but it doesn't change the fact that you can often find out as much about a culture from what they produce en masse as you can by talking to them directly. Or at least that is how it registers in my mind. Remember though that I am a weird ass guy who often looks to a culture's history, legends, and lore to better understand their mentality and how they developed into their current state.
I'm not saying they are all incestous, but like my own European ancestors, incest existed in their history and may still echo in their culture today.