From two of the world’s top scientists and one of the world’s top science writers (all parents) comes a q&a-based guide to everything you need to know about kids & germs.

“Is it OK for my child to eat dirt?”

That’s just one of the many questions authors Gilbert and Knight are bombarded with every week from parents all over the world. “My two-year-old gets constant ear infections. Should I give her antibiotics? Or probiotics?”; “I heard that my son’s asthma was caused by a lack of microbial exposure. Is this true, and if so what can I do about it now?”

Google these questions, and you’ll be overwhelmed with answers. The internet is rife with speculation and misinformation about the risks and benefits of what most parents think of as simply germs, but which scientists now call the microbiome: the combined activity of all the tiny organisms inside our bodies and the surrounding environment that have an enormous impact on our health and well-being. Who better to turn to for answers than Jack Gilbert and Rob Knight, two of the top scientists leading the investigation into the microbiome—an investigation that is producing fascinating discoveries and bringing answers to parents who want to do the best for their young children.

JACK GILBERT, PhD is a Professor of Surgery at the University of Chicago and Director of the Microbiome Institute.

ROB KNIGHT, PhD is Professor of Pediatrics and Computer Science & Engineering and Director of the Center for Microbiome Innovation at the University of California, San Diego. He is co-founder of the Earth Microbiome Project and American Gut.

SANDRA BLAKESLEE has worked for the New York Times for nearly 45 years, winning multiple journalism awards.