After installments that profiled Albert Einstein and Pablo Picasso, the Nat Geo dramatic series “Genius” turns to the life of the singular talent that is Aretha Franklin with “Genius: Aretha.” Cynthia Erivo (“Harriet”) steps into the giant shoes of this music legend, even admirably tackling some of Franklin’s biggest hits herself, as writer Suzan-Lori Parks (a Pulitzer Prize winner for “Topdog/Underdog”) jumps back and forth, connecting Franklin’s youth to the decisions she made and art she produced as an adult. It’s a smart program with resonant performances that sometimes falters due to shallow dialogue and inconsistent focus, but there’s enough to like here for fans of Aretha Franklin, which really should be everyone.