Box-and-whisker plots of sperm DNA fragmentation for different genotypes. The boxes represent the 25th and 75th percentiles; whiskers are lines extending from each end of the box covering the extent of the data on 1.5 × inter-quartile range. The median value is denoted as the line that bisects the boxes. Circles and asterisks represent the outlier values. Significant differences were measured by multiple linear regression.