Lorde's mom: George Brett photo was in Lorde's vintage National Geographic collection

Mystery solved!

On Thursday March 20, Sonja Yelich emailed us to say she enjoyed this article about her daughter Ella -- aka Lorde.

And she answered our question about how the teen pop sensation came across a 37-year-old National Geographic magazine, "Ella used to collect vintage National Geographics," her mom told us.