Well you don't have to delete EVERYTHING. You just need to figure out what file is causing the problem. To do this you can start by verifying what you suspect to be true. Remove your downloads folder (Cut and paste it to your desk top or any other place outside The Sims 2 folder that you will remember) and re-load your game (you may need to delete the .cache files from The Sims 2 folder). Then see if your kids turn out normal.. if so, it is indeed a bad CC file.
After confirming your problem, you can slowly add bits of CC back into your game and re-test. You may want to remove them again once you have tested so you know which files are okay. When you add a batch of files that causes the problem again - you know it's one of those files. Test those files in smaller groups until you pinpoint the bad file(s).
This can be a long and laborious process if you have a lot of CC. To make it easier, test any mods or hacks first (these are the most common cause of a glitch) and if those are clean, test objects. If you don't know which files are which, you don't have a very organized Downloads folder~ you can use a program such as the clean installer or Delphy's download organizer to get organized first.
If all of this is just simply too much to do, you can go ahead and delete everything and re-download what you like. If you don't know what file caused the problem to begin with though, you could end up installing the same bad file
