Songfacts®:

• On "He's Not My Baby, I'm His," Sienna Spiro unpacks the emotional contradictions of a relationship with a much older man. She examines why the imbalance felt appealing at the time, acknowledging both its unhealthy dynamics and her desire to feel seen, protected and chosen.
• The title turns a familiar pop cliché on its head. Instead of declaring someone is "my baby," Spiro sings, "He's not my baby, I'm his," establishing that this isn't a relationship between equals and she sees herself as the one being claimed rather than the one doing the claiming. That inversion also echoes lyrics in which Spiro admits to liking being told she's "too young to know," showing how affection and control can become tangled together in uncomfortable ways.
• Speaking to Zach Sang, Spiro revealed that the song was inspired by a real relationship with a man "twice my age." At one point she jokingly suggested he was "more than double" her age before correcting herself, but the underlying point remained the same: she had entered a relationship shaped by a significant age and power gap.
  
  Spiro connected the experience to growing up quickly and later trying to reclaim or re‑create feelings she felt she missed, such as being looked after, held, or having her hair stroked. The line "no one feels quite as seen as when a child gets chosen" captures that craving for comfort and validation; it's about the thrill of being singled out, even when the context is wrong.
  
  Although the relationship ended badly, and the man "did not have good intentions," Spiro said she learned from it, but won't repeat it.
• Spiro's "Great Expectation" was written about the same relationship, making the two songs companion pieces. While that track explores the fantasies and hopes surrounding the romance, "He's Not My Baby, I'm His" focuses on the darker mechanics of the power imbalance.
• Spiro wrote the song with her songwriter friend Lucy Healey after the pair spent time discussing the relationship. Healey, who contributed to seven tracks on Madison Beer's Locket project, sings backing vocals on the track as well.
• Emile Haynie (Bruno Mars' "Locked Out of Heaven," Tate McRae's "Nobody's Girl") also helped write the song and co-produced it with Spiro's regular producer, Omer Fedi.