Is glaucoma inherited?

Some are. There are many different types of glaucoma, some caused secondarily through trauma or other diseases. But there are some type of glaucoma where genetics are involved but not 100%. In other words just because your parents have it doesn't mean you have to get it. However, risk is certainly higher....
Not necessarily. Glaucoma is a diseae that leads to damage of the optic nerve. This in turn causes decreased peripheral vision, and can lead to total vision loss if untreated. Glaucoma has been found to run in families, and to be more common in certain ethnicities. Also, some "glaucoma" genes have been identified. Nonetheless, the majority of cases of glaucoma are not known to be inherited.
Frequently. Yes, glaucoma is frequently inherited, especially the more common types like open angle glaucoma. There are, however, many cases that are not inherited. In addition, all secondary glaucomas are not inherited (i.e. After trauma, iritis, neovascular).I practice in the mississippi delta where both blacks and whites have a much higher rate of glaucoma than the rest of the country. Many are inherited.
Can be. Glaucoma genes have been discovered and can be inherited .
Yes. Yes there is a genetic component (small percentage of the total), but the disease is still, for the most part, multifactorial. Thus genetic testing is not common since not all the genes for glaucoma have been identified yet. Glaucoma genetic studies are ongoing, including mapping out the phenotype.