Old wives’ tales are the cautionary tales we tell our children, passing down wisdom through generations. They often blend folklore with pseudoscience, but what does the actual science say? We surveyed clinicians who care for children in primary and secondary care for their favourite tales via the Don’t Forget the Bubbles Discord, which has more than 300 members from around the world (though predominantly based in the UK and Australia). After selecting the most popular, we conducted seven literature reviews, developing PubMed search strategies using MeSH terms and free-text keywords, and performing citation searches on relevant articles. When research was sparse, we broadened our search to Google Scholar and grey literature, to explore the evidence behind these time-honoured claims.

Of all the body’s sounds, older relatives love to warn children about knuckle cracking. But is there any science behind the claim that it causes arthritis? We cracked this myth open.

First, the anatomy. Knuckle cracking collapses the bubbles in synovial fluid, producing that satisfying pop. A case study (with one participant) conducted over a 50-year period compared a left hand that was knuckle-cracked (36 500 times) and a right hand that was not cracked at all.1 There was no correlation between habitual cracking …