I‘ve been trying to change a babys genetic hair color in SimPE but in the Resource Tree there is just no Age Data AGED file is there another way to genetically change the hair color or to find this file?

You could wait until they're a toddler. Not sure if babies have a full set of data.

It's possible to change their hair color/eyebrow color with a mod (Insimenator, simblender, or similar. make them selectable, then change their appearance via the mod). This should last until toddlerhood ingame, but isn't genetic.

Thanks, I waited until they‘re a toddler but there‘s still no Age Data

Babies should have a full set of data already.

I usually change hair genetics via the Neighborhood Browser - Sim Browser - More - Open Sim DNA. Maybe try that? There should definitely be Age Data in the character file though... I doublechecked with a baby in my own neighborhood to be sure. He has Age Data and his hair genetics are properly visible.

They have Age Data, if they didn't you wouldn't be able to play them without a ton of errors. It's probably just in the other half of the split character file. You don't need to change Age Data just to change the Sim DNA, though, that's a separate resource. If you want to change the hair color they actually use in the game, you can just do that with the mirror, there's no need to use SimPE at all.

I want to change the genetic hair color. If I just change it in the mirror their babys will also always get the hair color I don‘t want. Where would be the other half of the split character file?

Yes I did that, but as far as I understand that won‘t make any visible changes in the game

Yes, to change the Sim DNA you edit the Sim DNA resource. This is accessible from the neighborhood package, you don't have to open the character file at all.