Members of the cat family Felidae range from the great, roaring cats such as the lion and tiger to the small domestic cats. They are separated into different geneses (family subdivision), not because of their size, but because of differences in their anatomy. These enable members of the Panthera to roar, while the small cats in genus Felis cannot do so. There is a third genus for the cheetahs because they have non-retractable claws. Early in the 1900’s there were more than 230 different species of cat in the family as a whole, but now there are fewer than 30. Many become extinct because cats have always been hunted and killed by humans for their pelts.
There is a close relationship between the wild and the domestic cat, but it is uncertain which wild sub-species of the Felis (small cats) genus actually made the leap to domesticity. Experts ended up with three major contenders for the ancestor of the domestic cat: the European wild cat and its Asian and African equivalents.
This information was gathered from ‘The ultimate encyclopedia of cats’ by Alan Edwards