Why was the identity of Naruto's parents kept a secret from him?

Question

In Naruto, at the beginning and for a very long time, we had no idea who Naruto's parents were. At first, I thought it was because they were unimportant nobodies, but not at all!

So, why didn't the Third Hokage tell Naruto who his parents were? Why didn't Kakashi tell him? Or Jiraiya? 

I understand not telling him about being a receptacle, but why not tell him about his parents? And even after he discovers he is a receptacle, no one is telling him about his parents??? That truly doesn't make sense to me, and I even find it outrageous that they would hide such an important piece of information from him. They could have given him pictures of his parents all along and told him how his parents died (as heroes). But no, instead they hide it from him.

So, is there an in-universe explanation for this?

Answer 1

To avoid putting Naruto's life in danger

Naruto's father, Minato Namikaze, confesses to Naruto in Chapter 440 of the manga, "A Conversation with the Fourth!!" (Naruto: Shippuden ep. 168 "The Fourth Hokage") that he is Naruto's father. He also explains that Hiruzen (the Third Hokage) "wanted to suppress as much information about Nine Tails as possible," and that "if folks had found out [that Naruto was his] son, [Naruto] would have been in danger."

Minato was a well-known and powerful Konoha ninja who had fought and killed many of Konoha's enemies, some of whom might want to retaliate against Naruto if they discovered he was the former Hokage's son. Hiruzen thought it would be better to keep it a secret to keep their enemies from harming Naruto (and Konoha, by extension).

The Nine Tails, who had destroyed the village years before, was sealed inside Naruto, so most of the Konoha villagers shunned and resented Naruto. If Naruto had known his parents' identities, he might have told others in order to prevent them from mistreating him, putting his own life in danger.