Guinea hens do not know whether or not the eggs are fertile. When they have a big enough clutch, they will go broody.If you have chickens, it is possible that she has some of those eggs under. Only an inspection of her nest will let you know what is there. If you have a chicken rooster, it is possible for the rooster to breed the guinea hen allowing her eggs to be fertile.I have a guinea that is currently sitting 15 eggs...the problem is, she is the only guinea I have. I am wondering if maybe she is sitting on other hens eggs...could a rooster have gotten to her or is this typical for them to sit on unfertilized eggs? She won't let me near them, she is very protective of her nest...
If you can inspect the nest and candle the eggs, you should be able to tell whether they are developing or not.