It's possible, and implied, that Ender may have been retrovirally altered ...
(from Aramis's answer to Is Ender genetically-engineered? )
I don't recall any such implications in the books. Was that implied, and if so, where?
I couldn't find any mention of this in First Meetings.
But I did find a quote (Bean's thoughts to himself) in Ender's Shadow that could - if read incorrectly - be construed as implying this:
They flipped a genetic switch in me and made me an intellectual athlete. I can get the ball into the goal from anywhere on the field. But knowing when to kick. Knowing how to forge a team out of a bunch of players. What switch was it that was flipped in Ender Wiggin's genes? Or is that something deeper than the mechanical genius of the body? Is there a spirit, and is what Ender has a gift from God? We follow him like disciples. We look to him to draw water from the rock. (Ender's Shadow, Chapter 21 - "Guesswork")
Now, this is just Bean specilating about Ender and not really implying genetic engineering - but he WAS in the same sentence talking about retroviral genetic alteration in himself as a point of comparison. So a casual reader might get confused.