These images show how wild type genetic background affects how genetic mutations manifest. The fruit fly wings in the top two images are from two healthy individuals with different genetic background. The two middle images show how the same genetic mutation caused different outcomes in the two individuals' wings. Genetic background also affects how genetic mutations interact with each other, as shown in the bottom two images. In the image at bottom left, the two mutations together have a milder effect, while the same mutations are enhanced in the bottom right photo.