User blog comment:Bennlimos/Understanding the Zoldyck Family's Nen Situation/@comment-5780397-20151018161524/@comment-14902757-20151020061745

1) I think you're right about him knowing nen as some kind of power prior to HA Arc. After all, when they first agreed to train under Wing-san, Killua was aware that nen had "something to do" with his brother's powers. He was aware of it but didn't know what it was exactly. I tend to disagree however when you said that he never really questioned abnormal powers coz when you think about it, he had Alluka's powers figured out. When they were much younger, Killua wished from Nanika to tell him how to bring his little brother's face back to normal. That's all he knew - how to bring back Alluka. Alluka's powers were even more difficult to understand compared to nen but without further wishing, he got it figured out.  Given Killua's level of analytical capacity, he should have been able to know what these abnormal powers the rest of his family and their butlers use. A few reasons come to mind why he didn't seem to be as inclined to learn as we would expect while he was still at home. First, it appears that Illumi had full control over Killua's training. Enabling Killua to master nen at a young age would have caused him to become even more unruly (as was already suggested by one of the comments below). Then, there's Killua's preoccupation toward his job assignments as an assassin because he was very good at it. And finally his laidback & overconfident attitude. Killua is extremely talented but it showed that he's a little too confident of his skills as suggested by Biscuit later on in the CA Arc. He was even refusing Biscuit's offer to mentor them during GI Arc despite Gon begging.

2) Milluki accepts assassination missions from Silva and accomplishes them without having to leave the comfort of the Zoldyck estate. If he's a manipulator, I think he should be able to apply his nen to his hacking skills. Imagine the possibilities of nen in the world wide web. Even their www must be somehow influenced by nen since nen is programmable. Not being able to use nen could be a handicap for his trade since there must be some who does. What I'm saying is it's almost nonsensical to let fans know that he's a manipulator and a computer genius but unable to put those two to work together. I've been thinking that maybe back then he was just so curious about the game and never had a hold of anything related to it like ever (because of the impossible cost of the unit) that's why he accepted and to took on the challenge. After all, we never really witnessed how he tried to replicate the thing. It was not clearly explained.

3) I answered this here.

4) Kalluto seemed to be very close to Kikyo so I'm assuming that he learned nen from their mother. We all know what kind of person/mother Kikyo is, so my guess is that she insisted training their youngest even at a very young age. This is why I'm a little perplexed. Who decides the initiation? If some suggest that they allow them to learn it outside, wouldn't that be dangerous for their trade?

5) The reason I deduced that the family didn't want Killua to learn nen yet back then is because Kalluto obviously already knew how to use it when he is still even younger than Killua today than when Killua learned nen.  And yet, Kalluto is already extremely skilled at zetsu.

I think if Killua was already skilled and confident at a young age, it's unwise to not teach him nen because the odds of him going after tougher opponents (likely nen users) were higher.

Oh, my bad. I forgot about people like Hanzo. But wait, was it directly stated in the anime that Illumi implanted the needle during their match in the Hunter exam? I thought the needle goes way back.

I agree about their twisted love for Killua ad their expectation of Killua to reciprocate it-that Killua would come back to them because he loves them. Lol.

By the way I appreciate the long answers. And I respect your attention to detail.