From his biography from 2012:
When examining a subject's ancestry and early life it is important to draw a distinction between revelation and responsibility. No one wants to be judged or held responsible as an adult for how they behaved in their youth, or for how their relatives behaved. That should be neither the function nor the intention of a biographer. But there is an important difference between laying blame and searching for clues to a life, and many important clues come in the early years. The point in any case is to explore that territory in search of understanding, not retroactive condemnation. It seems obvious, but it demands explanation in the modern American political culture, where facts are so easily twisted for politcal purposes and where strange armies of ideological pseudo-historians — predominantly, these days, on the irrational flank of the political right — roam the biographical fields in search of stray ammunition.