For me it kinda makes sense: the portrait/person is an important feature of the image, so it's heavily weighted in the generation, producing another image with

For me it kinda makes sense: the portrait/person is an important feature of the image, so it's heavily weighted in the generation, producing another image with that portrait/person, and so on. I find it more interesting that the visage itself is still recognizable between generations, as if it's not "any person", but a very specific visage.