Keeping a house too clean can increase a child's risk for developing the most common form of childhood cancer, according to a new study.

Publishing in the journal Nature Reviews Cancer, study researcher Mel Greaves, a professor and biologist from The Institute of Cancer Research in London, reported on his analysis of about three decades' worth of data.

The study suggests a child's risk for the cancer starts with a genetic mutation in the womb, which about 1 percent of people develop. And among those with the mutation, having an overly clean house in the first year of life increases the risk of developing acute lymphoblastic leukemia, the study found.

ALL accounts for about one-fifth of all cancers among Americans under the age of 20, according to the Centers for Disease Control and Prevention.

"It has always struck me that something big was missing, a gap in our knowledge – why or how otherwise healthy children develop leukemia and whether this cancer is preventable," he said in a news release.

"This body of research is a culmination of decades of work, and at last provides a credible explanation for how the major type of childhood leukemia develops."

Greaves used a variety of different cases to come to the conclusion. For example, children with older siblings in daycare had a lower rate of getting the cancer, while those born vaginally — and exposed to more microbes — had a lower rate of developing leukemia when compared with those born by C-section.

The study also found breastfeeding reduced a child's chance of coming down with the childhood cancer, possibly because it introduces a child to more microbes.

"Be less fussy about common or trivial infections, and encourage social contact in the first year of life with as many children as possible," Greaves advised. "And actually, contact with older children is probably a good thing."