“There’s no home test kit where Olivia Rodrigo can do a cheek swab and find out she’s three percent Rites of Spring, but if you believe in musical genealogy, there is a line you can trace from the hardcore punk of Washington, D.C., circa 1984” to Rodrigo’s tenacious sophomore album, I wrote in a piece charting the zigzag lineage of emo. Not explored in that essay: the other 97 percent, an apparent blend of Weezer, Avril Lavigne, Bikini Kill, Romeo Void, Regina Spektor, the Waitresses, the Cars, the Strokes and umpteen other inspirations that seems to prove that, for pop stars in the information age, sounding like an uncountable number of other people is a good way to sound like yourself.