“On paper, they should be commercial death,” New Zealand comedy writer Paul Horan says of Jools and Lynda Topp, a yodeling, country-and-western-crooning lesbian sister act. But the beloved Kiwi duo, who frequently perform as a rotating cast of corny alter egos, can charm even the crankiest viewers, thanks to their soaring, clarion harmonies and cuddly-butch personas. Born in 1958 on a dairy farm, the once severely mulleted twins busked on the streets of Auckland, releasing their first album in 1982. Three decades later, they still stop at tiny county fairs while on tour (concert crowd-pleasers include “Calf Club Day”). But the Topps’ act is more than just bovine odes: Director Leanne Pooley intercuts performances and interviews with archival footage of the sisters’ unwavering political activism over the years, including protests—and songs—on behalf of Maori land rights, a nuclear-free NZ, and homo equality. That the Topp girls were never in the closet is, of course, its own kind of political act. In a clip from a 1982 TV segment on the sisters, a narrator, who sounds as if she’s reporting on an alien species, announces, “They sing about homosexuality, and people don’t seem to mind, perhaps because they look wholesome and have such an irrepressible sense of fun.” Pooley successfully conveys that joie de vivre, erring only when including too-invasive scenes of Jools’s breast-cancer treatments.