We live in the UK. I have a child who was diagnosed with ALL and successfully treated. He is now 18 months post treatment. He did have a very serious infection at the time of diagnoses that was a major threat to his life at the time. However, we don't fit this proposed model. This was our third child. We don't run a "clean" household - we don't use antibiotic soap, we skip meat raised with antibiotics and we did not run to the GP for antibiotics for every sniffle. My wife breast fed all our children from birth past one year of age. We allowed the children to play in the dirt, eat a bit of sand in the sand box and just generally have fun outside. We don't doubt that gut priming is important but this theory does not explain every case. I understand that the researcher does not claim it explains every ALL case. I just share this for those who are wondering what they could have done. I think we ticked all the boxes of gut priming and our child still got ALL. Be at peace.