Forget CDs, books that beep, and toys that whirr. When it comes to child development playing music trumps them all.

Forget the Mozart Effect and Baby Einstein, take it easy on acquisitions for your two-year-old’s private library, and don’t fret if your three-year-old hasn’t started violin lessons just yet. The key to unlocking a child’s potential intelligence and happiness may indeed lie in music, but succumbing to the commercial juggernaut that is the baby-genius-making industry may not be in either your child or your wallet’s best interest.

Instead, try making up songs with your toddler. A new study suggests that regular informal music-making with very young children may even have benefits above and beyond those of reading.But there’s an important, interesting, and somewhat beautiful catch – for best results, make it shared music-making in your home. In an analysis of data generated from a study involving more than 3,000 children, a University of Queensland team investigated the associations between informal home music education for very young children and later cognitive and social-emotional outcomes.

The team found that informal music-making in the home from around the ages...