‘Family Name’

New York filmmaker Macky Alston (pictured), descended from North Carolina plantation owners, believes that because much of his own life involved a secrecy--he is gay, and he only came out to his parents at age 19--he was driven to delve into other kinds of family secrets, to pore over actual documentation of his ancestors’ ownership of slaves and to discover blood relations between the black and white Alstons. The first task was relatively easy, the second, far harder. As a filmmaker and as a family historian, Alston learns as he goes along, which imparts his film with a beguiling sincerity. Not surprisingly, Alston finds both white and black Alstons reluctant to talk about a painful past. Yet by the time this unforgettable 1997 documentary is over, Alston has filled the screen with Alstons of every shade, creating a powerful image of the unity of the human family (KCET Tuesday at 10 p.m.).