alt Hacker NewsAs a general rule, someone trying to use a simple single numerical measure as a skeleton key to understand politics across nations is an ideologue with an agenda.
As for the Genghis Khan comparison, I may have made an error. We may just be dealing with severe cognitive limitations here.
If you think slavery is the key to explaining everything about the US, the burden of proof is on you to show that. Just because something gets discussed a lot does not prove that it's important. Donald Trump is himself the child of immigrants who immigrated to the US well after the end of slavery, and maintained a residence in a state (New York) which opposed slavery. The relevance of slavery to his presidency is at best unclear.