User blog comment:Bennlimos/Understanding the Zoldyck Family's Nen Situation/@comment-5780397-20151018161524

There could indeed be some plot holes, but some of your assumptions lack a concrete basis, though they are reasonable. I'll try to share my views:

1- Killua never showed a sign of suprise when learning about Nen and its powers. He had seen Alluka do the impossible, and probably had heard about his relatives' powers, but might have simply assumed they were simply due to their strength, training and other mechanics he did not understand. Perhaps exactly because he had Alluka in his family, he had never really questioned it, as occurrences that defied common sense were an everyday thing to him. He might have simply assumed that some humans have special abilities, while others don't.

2- The Databook revealed Milluki to be a Manipulator, if I recall correctly. However, he might simply be terrible at it, to the point he can't use Gyo or even release his aura at all. Just like Killua, he knows of Alluka and Illumi's abilities. Besides, what Killua had sent him was not Greed Island, but a copy of it: that could be the reason why he was uanble to access the files. That game was created by exceptional Nen users, one of which is even more skilled than Netero, while Milluki might not even be able to use basic techniques, or if he can and has developed a Hatsu, there is no concrete proof it allows him to manipulate computers; hence, it is not surprising he failed, also keeping into account that he does not seem to be undergoing any kind of training. That said, while it is sure that he is a Manipulator who comprehends the effects of Nen, we cannot assert he is able to use it himself.

3- This point has been discussed several times; my only guess is that he learned all about them right after passing the Hunter Exam, when he got his yo-yos from Milluki. Another possibility would be that he had already seen Illumi's Needlemen and Zeno's Dragon Dive (in the second case, Zeno preparing a technique and the target being bombarded by an invisible attack), and simply ignored how they were able to use them.

4- Zoldyck children seem to receive training both at home and away from it; Kalluto might have learned Nen this way, or simply he might have shown to be so talented in this field - or possibly so lacking in others - that his family decided to teach him. The training of all the Zoldyck kids is visibly different, after all. Milluki might have refused to train, and when heading to the auction, he stated he had not left the house for something like 10 years, I believe, so he would have been unable to learn Nen either way.

5-    I don't remember, where does it say that they did not want him to learn Nen yet? Anyway, t hey might have realized he was ready to learn it when he left with Gon and the others. Silva was also sure he would come back one day, I don't think he would have want to risk angering him by having him followed. If tehy did not teach him before, it might have been because he was so talented in martial arts and other forms of assassination that his training had focused exclusively on that.

As for your other points, my opinion is that his family did not want him to get killed in a fight with a Nen user, not prevent him from learning Nen.

- That is not true. Hanzo, to name one, was stronger than Killua even when they were ignorant about Nen, by Killua's own admission. Same for Hisoka. Besides, how could they know that Killua would not end up facing an opponent who knows Nen, be unable to grasp his or her power, and die in battle? That is precisely what could have happened when he played that ball game with Netero, where he was entirely convinced he could have killed the chairman if he had gone all out. The part about the needle reacting to other people's Nen is a good theory, but that is exactly what it is: a theory. Killua was already paralyzed by Illumi's aura before the needle was embedded into his brain, and Gon, too, was able to feel it after Killua's disqualification.

- In their own twisted way, the Zoldycks love each other: Kikyo tortures her children but is extremely attached to them, Illumi loves Kullia but is willing to control him and even die so that he can become a burden on his conscience and be remembered forever. Killua was 6 when he faced the Heaven's Arena, it's not surprising that they did not want him to face opponents that had trained in Nen as hard as he had in martial arts, especially since he would have been unable to sense their power.

- Yes, but we don't know if they consented to it; while this is probably the case, the needle was implanted after Killua run away from home and wounded his mother. They might have even encouraged Illumi to use the needle to keep Killua safe, as, being a Hunter, he would run into many Nen users or people stronger than him. Again, it's their twisted love that moved them.