The Washington Post recently used the word "troubling" in a headline describing Mitt Romney's behavior as a teenager, and insisted in a subsequent column that his conduct in 1965 plays a vital role in providing clues to his current character.
Remarkably, this is the same newspaper that has featured commentaries by terrorist kingpins and never used a term as negative as "troubling" to identify them.
I think biographical stories on presidential candidates are fair game even if controversial incidents contained in them are far in the past. Of course we all change and mature. But these stories give clues to the character of the flesh-and-blood human beings we pick to lead us.