A Planet Called Treason

A Planet Called Treason is a 1979 novel by Orson Scott Card, later slightly revised and re-released as simply Treason.

On the titular planet, a group of families were banished by The Republic over three thousand years ago for arrogantly attempting to usurp the goverment and install a meritocracy where only the intellectual elite (read: them) would rule. Treason, despite being a habitable planet, contains very little iron (and none of it easily reachable by the surface), so the families were essentially doomed to live out the rest of their lives in primitiveness. However, The Republic decided to throw the families a bone: small teleporters, given to each family, called "Ambassadors". Place something of value in the Ambassador, and if The Republic deems it satisfactory, they will send back a lump of iron in its place. Three millenia on, the families have become warring nations, fighting on horseback and with swords over the iron, each in a race to become the first family to finally build a spaceship and escape Treason.

Lanik Mueller, the 16 year old heir apparent to the Mueller throne, makes a dark discovery about himself. The Mueller family was founded by a geneticist, and over the millenia their genetic expertise let them gradually improve their own DNA, to the point where the Muellers are well-known for their incredible Healing Factor. Able to regrow limbs and shrug off injuries that would normally be mortal wounds to other men, the Muellers are fearsome on the battlefield.

However, the Muellers' gift comes with a downside: occasionally, a few times a generation, a Mueller is born whose Healing Factor is cranked Up to Eleven. Despite looking normal as a child, this "radical regenerative" Mueller begins sprouting extra legs, arms, and other organs in adolescence. Try cutting off these extra limbs and they just grow right back.

Lanik is one of these "radical regeneratives", and as he begins to sprout body parts he should not have, he is shamed from royalty. His father, the king, spares Lanik from death or the fate of other radical regeneratives (which is to be treated as cattle, repeatedly having their extra limbs cut off and fed to the Ambassador for iron). Instead, the father sends Lanik on a mission to one of the neighboring nations called Nkumai, which used to be peaceful but recently and suddenly began warring and conquering other nations while wielding improbable amounts of iron.

This book provides examples of:

 * Healing Factor: After hundreds of generations of eugenics, the Muellers are able to heal ridiculously fast, even from injuries that would normally kill anyone else, such as having an arm lopped off or a throat cut out.
 * The only things that are sure to kill Muellers is beheading, a fall from a great height, or drowning.
 * Hermaphrodite: Apparently a normal phase for Muellers in puberty, with their "real" sex eventually winning out. Unfortunately for radical regeneratives, this becomes permanent, since the out-of-control Healing Factor can't distinguish between what's genuine and what's not....
 * The Grotesque: Lanik. At first his radical regeneration just gives him breasts, but as time goes on he starts growing an extra arm on his back. And then another. And then an extra leg, and another...
 * Used by Lanik later in the book after he's captured by slavers. They throw him in a hold on their ship, not knowing what he is. While down in the hold, he continually grows new limbs and nearly losing his mind. After a while, he begs for them to let him up and see the sun. They open up the cell...and immediately back up in fear. Seeing a chance to escape, Lanik plays on their fear, roaring and scuttling around until they let him go.
 * Penal Planet: Treason was this for the original rebels and continues to be so for their descendants.