AlPaar

Chimps! Though we share 98% of DNA with the chimps, still we are genetically diverse with them and a cross breeding is in tough scientific and ethical grounds. Quite a few researches had created chimeras between Humans and rabbits, mice, pigs and other animals. But a full hybrid with humans on the other hand is not that easy.

I did not mean to imply that it is possible. It’s just not that easy. The definition of the taxonomies is so hardly rooted in a single statement that defines them. Two animals can be put inside a genus if they can reproduce and form a fertile offspring. XXelianXX’s answer puts this in a simpler manner. Early humans bred with Neanderthals (different species – Homo neanderthalensis). It is the way we classify them.