Under normal circumstances, kittens can eat egg yolks in moderation. Egg yolks are a nutrient-rich food, containing protein, fat, vitamins, and minerals. They are high in fat and cholesterol, so they should be consumed in moderation.
However, there are a few points to note:
1. Kittens' digestive systems are not fully developed, so do not give them too much egg yolk or too frequently to avoid digestive problems.

2. Ensure the egg yolk is fully cooked; never feed raw egg yolks to kittens. Raw egg yolks may contain bacteria or parasites, which can be harmful to a kitten's health.
3. If kittens are already eating fully cooked cat food or wet food, they are usually getting enough nutrition. Egg yolks can be given as a treat or occasional supplement, but should not be their primary food source.
Most importantly, every cat's health condition and dietary needs may differ, so if you are concerned about your kitten's diet or are preparing to give it special food, please consult a veterinarian for proper advice and guidance. They can provide appropriate dietary recommendations based on your kitten's specific situation.