When Borat – alias British actor Sacha Baron Cohen – told risque jokes about Donald Trump and antisemitism at last month’s Kennedy Center Honors in Washington, Joe Biden was not the only one laughing in a red velvet-lined balcony. Sitting behind the US president was Hunter Biden wearing black tie and broad smile that mirrored those of his father. The image captured the intimacy between the men but also the sometimes awkward status of Hunter as both private citizen and privileged son of a president. It is a dichotomy likely to come under a harsh public glare this year as...