Feel free to ignore this thread or not post at all if any of the subjects bother you. It's just my summation of thoughts after much discussion and reading what others have posted.
Summing up any family as a whole is wrong. And it does nothing to help any theories, there are always exceptions. Everything comes down to the potential of the bloodline and the individual. For instance certain members of each family are special, the requirements to being 'special' are;
1. be born into one of the magical families; Starks, Targaryens, Blackfyres, Boltons
2. have the luck to be a member of that family who is able to access the inherent magic that comes from that families bloodline
3. be an individual who makes the right choices to harness that magic.
Like what Butterbumps was saying on her thread about the Boltons, that Roose is actually a lot older than he appears. that the boltons have magic in their family. Roose has taken the right steps to ensure his youthfulness, by blood sacrifice (possibly of his children) and the leeching. Not every member of his family can do this, but he can and he made the right choices to make it work for him.
Not all Starks are wargs, but they do have the warg 'gene'. Some of them are able to access it and some can't. Ned, Benjen, Brandon and Rickard are all not wargs, but obviously the children are. There is argument that Lyanna was, but we will probably never know, but Ned and Lyanna still had the gene to pass to their children, even if they themselves were not wargs.
That's why we can't group any entire family into one 'rule' or 'standard'
Some Targs can ride dragons, and some with just a drop of dragon blood, cannot.
Some Targaryens can get sick and they can get burned. They are not (as a whole family) immune to fire or sickness.
However some Targaryens "Have a higher-heat tolerance than ordinary people" (SSM).--Which is a quote that could be interpreted many ways, but I think it is clear that it means that the 'heat-tolerance' varies from Targ to Targ. Dany obviously shows, on many occasions, of being tolerant to 'heat' in the form of fire (in the Pyre, the HOTU and the pit). but then in the pit her skin was in fact blistered by the hot metal spear. So obviously she can be damaged by hot metal, just like Viserys and his crown of gold (there is obviously a difference between fire and hot metal when it applies to Dany, but we don't know about Viserys). And Jon Snow being burned by the lantern fire at The Wall, Jon is a good person and a strong Targaryen, but he shows no signs of the 'higher heat tolerance' like Dany does. I think Dany shows stronger signs of the heat-tolerance than any other Targ we have ever met. Aegon V also shows signs of having a high-tolerance during his travels with Dunk in D&E, but again we have no examples of him around fire specifically, just that he doesn't get hot and sweat the way 'ordinary' people do in the blistering heat of the sun.
It is sort of like an anomaly within the Targaryen family (like Neo). If enough Targ children are born, odds are that a few of them will have just the right genes and make-up that they have a much higher heat tolerance than others and vice-versa, some of them are born with no heat tolerance advantage and no specialities. But even the ones who are born with it, simply having a higher-heat tolerance does not make them superheroes, and anyone on this planet who drinks wildfire will have the same outcome and die. Dany could not drink wildfire, that is just a stupid idea, just as stupid as jumping into a river of lava.
Same thing goes with the sickness immunity, some have it stronger than others. but obviously it is a real thing or it would never be mentioned in the books. Dnay has never been sick, nor caught a disease. She doesn't say it directly but I think it is safe to assume Viserys never did either because Dany never mentions it when she is thinking back on how she never got sick, and if he had gotten sick then she would never be thinking 'members of my family cannot catch disease'. However that does not mean she is completely immune to all health risks in the world. It's not like she had Rhaego then jumped up 5 minutes later to get back on the horse, she was out for days. Just like when she has the miscarriage in DwD, that is a health problem, but not a disease, it was possibly brought on by food poisoning, which she can also get. If I had to guess I would say no virus can live in her body or attach to her cells, but she can have health problems. But there is no evidence that every member of her family is the same as her. Several Targ's died in the Great Spring Sickness.
Does that make sense what I am saying? that there are no 'rules' that apply to entire families, we have a few certain members of each family that have their families 'magic' gene.
Edited by Suzanna Stormborn, 16 June 2014 - 09:37 AM.