These controversies are peculiar to societies obsessed with group identity politics.
If Boyden's novels are well received good for him.  Free societies don't regulate what people can write about.  
And free societies allow people who are wound up about "cultural appropriation" to NOT read books written by authors they have a problem with.  Such as being dodgy about your ethnic background is that is the case.
(I await my mandatory DNA profiling to see if I qualify with Ms. Lederman to write novels about Poland and Ireland.)