Genetics of Head Size (image) Duke University Medical Center Caption Here are images of live zebrafish that were studied for genetics and head size to give insight into human head size. The top fish does not have the gene KCTD13 and its head size and brain size are larger; the middle fish is normal; the fish on the bottom expresses too much of the gene and has the smallest head and brain size. Credit Christelle Golzio, Duke Center for Human Disease Modeling and Duke Department of Cell Biology Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.