A child’s skin barrier is still developing. On the lips especially, it’s thinner and more permeable than an adult’s, which means ingredients cross into the skin faster. That’s exactly why an adult lip product — however "clean" — isn’t automatically right for a seven-year-old.
Formulating for children means starting from that biology: fewer, gentler ingredients, food-grade oils, and no synthetic dyes or fragrances that a developing barrier shouldn’t have to process.