Story ID: Boy who is stuck at 5 years old with robot nanny

Question

Here's what I remember:

• The boy is 5 years old, and has been for some time, because there's a bit in which he recalls turning 5 (celebrating his 5th birthday) many different times

• There's a robot nanny in the apartment with him that he learned to disable so that he can hang out with the girl, who he isn't supposed to know. (In my mind the nanny bears somewhat of a resemblance to Muthr from the Wondla series... however I definitely read this story well before reading Wondla)

• There's a neighbor girl who teaches him to read (I think she's like 9), and when they first meet she asks how old he is (5 is the last age at which growth/development can be successfully (and safely?) suspended) and he lies, saying that he's 6, but doesn't know why he does.

• When a child whose aging process has been stopped learns how to read, they begin aging normally again, so the parents don't want them to learn to read.

• The children who have stopped aging are kept apart from other children who grow normally-- they have separate playgrounds and the like

• The injection/serum used to halt the aging process was developed by a scientist, who when he first shared his findings had a 5 year old son and injected him, then told the onlookers/potential buyers/other parents to come back in 20(?) years. When they did, their children were adults and no longer needed them or were ungrateful layabouts, and the scientist's son was still 5 years old, cute, needy, etc.

• The main character has a discussion about how he wants to turn 6 with his parents and they agree but only because he's already learned to read and it's irreversible.

• It's kinda dark and emphasizes the need that parents have to feel wanted.

  Please help! I remember it so vividly and I'd love to read it again!

Answer 1

This may be “Infinity Jinx” by Margaret Peterson Haddix, which was asked about in this reddit thread and identified as the correct answer. It's also one of the stories asked about in this question about an anthology (which doesn't make it a dupe, however the answer does verify that "Infinity Jinx" is in the book).

This blog post gives a brief outline of the story's plot which hits on some of the specific points you remember:

What if children stayed as just that, children? After the terrible twos and troublesome threes but before the rebellious age of the teenager who no longer wants to hug or be seen with you. At that age where they love you, listen to you and think you are the coolest parent in the world and await Santa’s yearly arrival? That idea is explored by Margaret Peterson Haddix in the Infinity Jinx as the protagonist is 5, it's a bit hazy but he can remember his birthday last year also being his fifth birthday and the one before that. It's an interesting concept with good and bad sides which she explores in this wacky world of forever five.

...

In this world there are two segregated groups; those who age and those who froze their children in time. The two never mix, the two aren’t even really aware there is are children different to themselves.

...

When mommy and daddy are at work, the robot-nanny is there to care for him by cooking, cleaning and guarding the door when the doorbell rings until the person leaves.

(FYI, I found it by searching "Jeffty is Five", the story I immediately thought it was from the title, and "robot nanny" assuming somebody might have connected the two stories somewhere as they both deal with eternally-five-year-olds).