"Animal-Human Hybridization"
After the majority of governments on Earth decide that animals share the same basic rights as humans, consensual relationships between animals and human beings were finally allowed.
While most of humanity was not affected by this decision, there was a surprisingly large group of people who thought it wasn't so bad. Through the miracles of science, inter-species breeding was finally introduced to those who found them selves in early animal-human households. Through only two generations of this scientific process, which most people labeled "disgusting" and "weird", it was no longer needed as the chromosomes had built a world full of people who had the urge to hump legs and scratch-up wooden furniture. Most people of the planet regarded this as a "bad move".
