I think given how much influence this had on who he is now, it's just one of the things that shouldn't be left so open to speculation.
The omission of these details has driven me crazy from the very beginning.
I included Kakashi as one of Naruto's caretakers on my earlier post, but his involvement was actually later -- not during Naruto's apparently lonely formative years. Back in chapter #3 we see Hiruzen and Kakashi in Naruto's apartment observing the mess and the spoiled milk, and Kakashi says, "So this is where Naruto lives...?" Clearly he had NOT been involved in Naruto's life before Hiruzen decided to assign Naruto into his care as a part of Team 7.
That leaves Hiruzen and Iruka as the main responsible parties (that we know of) for Naruto's early care. In chapter #1 Naruto makes the comment, "Like I care, it's not like I have anyone to go home to..." Iruka looks sad/guilty/depressed, and later, when Mizuki threatens and berates Naruto, Iruka says:
Naruto must have been in a lot of pain? Must have? Really? Iruka figured that out just then? With a heavy dose of irony, Iruka's own inability to comprehend, anticipate, and prevent Naruto's pain sooner only proved that neither had the training or socialization to understand the basics of human need. They were a lot alike, and Iruka was better off since he'd had his parents for a while before they were killed.
And while Iruka might have been cast in the role of big brother to Naruto, I seriously doubt he was the one feeding Naruto and changing his diapers from birth to whenever he began living alone. But who was it? Hiruzen's wife, Biwako, and Taji (the other midwife present at Naruto's birth) were both killed by Obito. Who did Hiruzen entrust with baby Naruto's basic needs?
I had thought maybe we'd get the answers during Kushina's flashbacks to the birth, but no. Kishimoto shows us panels of Kushina meeting Mikoto and baby Sasuke. We find out Sasuke is named after the Third's father. Whoop-de-doo. We later see Itachi holding baby Sasuke, commenting on the fearsome chakra of the Kyubi. Kishimoto shows us those specific but seemingly unnecessary focuses on Sasuke, but fails to provide background information on Hiruzen's reaction to his wife's death and his thoughts on how he was going to care for Naruto going forward? I don't get it.
It seems to me that considering Obito's direct participation in the events of the night of Naruto's orphaning and his subsequent spy network, Obito is the only character still in play who might have the information on what happened and how Naruto was raised, but that's a super long shot. I think it's too much to hope that he'll provide such details if/when he gets a TnJ.
If an explanation never materializes, then I guess Kishimoto considers the details of Naruto's childhood to be irrelevant to the plot, and that he's given us enough to understand Naruto's psychopathology and take it face value.