Kinslaying is an age-old taboo with good reason: Your inner social group must be able to count on you under ALL circumstances and the differenciation between those who belong and therefore are to be protected and those who are outsiders, "everyone who is not us", was necessary for survival in traditionally structured small social groups. With a more elevated agricultural economy ownership of land and cattle was the basics for wealth, family members were either the workforce or in the nobility those who enforced the ruling over dependant peasants and whose solidarity was absolutely necessary to keep the influence of their own ruling class family.
So the commandment of absolute family solidarity, and the taboo of kinslaying is the ultimate form of it, has been seen as necessary as female virginity and "fidelity" in marriages to ensure the correct inheritance lineage and the absolute power of fathers to give their daughters into politically and economically advantageous marriages.
A society calls something a "taboo" because following that particular rule either cannot simply be explained by common sense reasoning or because following this particular rule is overwhelmingly important, therefore mythology and ideology are used as ultimate weapons, in pre-modern societies more effective than physical punishment.
Religious justifications of all those taboos above are therefore nothing but the ideological veil to keep the patriarchial structure of society upright because for those in power, male adults, it was the most comfortable form of survival. And those not in power, children and women, gained at least protection from abuse (of more than one person, father or husband) and food and shelter, often some comfort and luxuries.
The idea of "taboo" and "sin" and of what is "cursed" therefore did not start as a given ideological command by religion but it developed as the result of economical necessities.
Now obviously very early in the philosophical history of mankind the idea has developed that killing, hurting and oppressing other people is just wrong and sometimes philosophers and religious thinkers, which basically are nothing but philosophers, were able to free themselves from societies' ideological limitations, declaring absolute and universal rules of "what doing the right thing" means.
But nonetheless it is very interesting to follow how the taboos switch: in classical Rome kinslaying did not apply on unwanted children, especially girls, they were not needed as heirs. Girls as economical liability are superfluous in large parts of India and China. In many societies "euthanasia" of handicapped and very old people has been practised, not always because of nazi ideologies but in extreme survival conditions out of economical necessity, cruel to us, normal to them. So the group of those seen as worthy of moral consideration has always been a little flexible.
The idea that every human individual has the same value, no matter if he or she is slave or Lord, able or handicapped, has been promoted, as agnostic I have to grudgingly admit and admire it, by Christian philosophy, athough this religious ideology has as well given reason for several cruel crimes in human history. With the age of renaissance and enlightment the worth of a person not as part of a larger structure like family but as individuum has been further established. That was possible through the background that with advancing cities , manufacture and capitalist economy the individual workforce was wanted and in the leading economical centers of upcoming modernity migration and the dissolving of traditional family structures started.
Societies got a law system that recognized each murder as equally condemnable. With the advancement of human awareness in society the law enforcement system realized that old feudal ideologies were not helpful anymore, like killing your wife and daughter for the sake of the family's "honor" is simply murder. The taboo of kinslaying was certainly applied a bit more freely when it came to beating up your sinful daughter or your (not blood related) wife a little too intensely. Sexual "deviation" is not a crime anymore. And if the less powerful in oppressing structures strike back it is viewed as murder first or second degree or even more mitigating circumstances are granted.
So the taboo of kinslaying, that in feudal societies mostly existed upwards in a selective manner - woman killing husband, child killing parent, much less the other way round - has become simply a crime that has to be judged, like any other serious crime, in the light of maybe mitigating circumstances by a working legal system.
Of course this "taboo" was very much alive in a society like westeros, for good economical reasons, coated by different religions and ideologies.
But GRRM is inviting us in so many cases to look at a quasi medieval society with modern eyes concerning sexual politics, class structure and slavery. So we are invited as well to question other ideological structures like th law system and the idea of family obligations, forced and arranged marriages etc.
Of course the books are fantasy. And if Martin had wished to introduce a magical taboo that whoever eats forbidden apples may drop dead, he could have done so, that is his freedom as writer. But there is no reason for me to believe that the existing taboo of (selective) kinslaying is anyhow magically enforced. Of course it is very helpful in a society to burden the breaking of a taboo with various magical and religious constructs to make people respect it. The concept of "sin" has been invented for that. And so happily fornicating is a serious sin especially for women - mummy's baby, daddy's maybe.
And for those crimes that can even more undermine society's structure like (selective) kinslaying magical and religious condemnation had to be extemely serious. This, by the way, counts for guest right as well: alliances based on common agreements had to be absolutel reliable in pre-written contract times.
Condemning a baby for killing the mother during birth of course defies every modern idea of justice, it is simply absurd. And present day justice would certainly make a difference if a sexually and emotionally abused person kills his parent in emotional despair or if he simply wants the family money a little earlier.
But apart from those superstitions around the kinslaying taboo there are no extra added magical powers who especially pursue kinslayers so far. This may though be constructed later but Martin as well would be free to introduce e. g. the idea of special powers only mastered by cripples like Tyrion or Bran or handicapped like Lollys or Patchface as well, this is fantasy.
So far Tyrion is burdened with the taboo of ( presumed and real ) kinslaying, an enormous load for his future survival in Martinworld but there is nothing magically added to it. He is burdened as well with society's superstitions against those born handicapped and so far Martin has neither given him a magical advantage or disadvantage by it. (I would love to see some strong magic woven only by Penny, Tyrion, Lollys, Shireen, Patchface, Bran etc.... SHOW THEM!

)
But I do not think at all that any character is doomed to death per se by crimes or sins or has to buy his right of survival by a successful redemption so that we as readers can feel morally superior by rooting for the good guy or girl, feeling morally uplifted because the questions of good and bad are so easy to answer. No, not in these books.
Whether Tyrion is seen as kinslayer in Westerosi eyes may pose serious practical problems for him, which of course can be written away if Martin wishes to do so. And the character Tyrion may, and this is very well possible, finally run out of luck, the dwarf with the hundred lives may stretch his luck one time too much, there would be a certain plot logic in it. Though I would wish for him a bravado finale, crazy, awesome and well written - and only on the last pages, please.
Edit: and Lummel, a plot turn for Tyrion you gave above is well possible imo.
And I predict we will see far more signficant kinslayings when the story goes on, like Roose slaying Ramsay or the other way round, Jaime slaying Cersei or the other way round, Euron - Victarion, maybe Aegon - Dany, Arya - Sansa.........
Edited by Woman of War, 27 April 2012 - 04:02 AM.