Here is a link to that study
They picked 3 cities for this "control group".
1) Nagasaki: previously bombed by an atomic bomb
2) Yamanishi: Listed as heavily contaminated by the Japanese government
3) Aomori: Just north of Fukushima, many articles on severe contamination from Fukushima.
They tested around 4500 children, but DID NOT provide the overall test results. I have asked the author for the full results, we will see.
One of the cities had been bombed by an atomic bomb, and we know that genetic problems created by radiation do get passed on down the generations.
Another was Yamanishi, an area just on the other side of Tokyo. It would have been far better to pick a spot further removed. Yamanishi was a site published November 12, 2011 by the Japanese governement of having extensive radiation contamination
Cesium-134 and Cesium-137 soil contamination mapOn 12 November the Japanese government published a contamination map compiled by helicopter. This map covered a much wider area than before. Six new prefectures Iwate, Yamanashi, Nagano, Shizuoka, Gifu, and Toyama were included in this new map of the soil radioactivity of cesium-134 and cesium-137 in Japan. Contamination between 30,000 and 100,000 becquerels per square meter was found in Ichinoseki and Oshu (prefecture Iwate), in Saku, Karuizawa and Sakuho (prefecture Nagano, in Tabayama (prefecture Yamanashi) and elsewhere.
Finally they picked Aomori, also quite close to Fukushima and numerous articles about Aomori being heavily contaminated by Fukushima.
A variety of mushroom called "sakura shimeji" picked in Aomori city was also found to be slightly in excess of legal standards in October. All fungi picked in Aomori city disappeared from store shelves after the prefectural government issued instructions to halt shipments.