Sheep milk yogurt is an avoid for Os, as all yogurts are. However, on the genotype diet, every genotype is allowed some cheeses- though the specific choices vary from one genotype to another. Os following the Genotype Diet are either Explorers. Gatherers, or Hunters, and all 3 of those types have a few creamy cheese choices, such as ricotta, quark, or paneer. People with SWAMI (computer program that computes individualized diets) almost always have some cheese options as well, although these may vary from the ones in the genotype diet book, and some of the portion sizes are REALLY tiny, to where cheese is used as a condiment only.
If you're sticking with BTD, you can use goat cheese in many of the places you'd otherwise use yogurt- but mix the cheese with some water or oil first to get a creamier texture.