Glaucoma IS hereditary.

Glaucoma is actually a set of eye disorders grouped under one heading.  Risk factors for several forms of glaucoma include family history.  It is estimated that your glaucoma risk increases up to nine times if you have a family member with glaucoma.

A person who is non penetrant can carry the muted genes that cause glaucoma but never develop the disorder.  Though never having had glaucoma, this carrier can still genetically pass the disorder to children.

Primary Open-angle Glaucoma: Hereditary

Primary open-angle glaucoma is the most common form of glaucoma.  Though the specific genes that cause this form of glaucoma have not yet been identified, it is considered hereditary based on collected data.  Risk factors involve family history in tandem with other factors such as environment and interaction with other genes.

Early-onset Glaucoma: Hereditary

The term early-onset glaucoma is used when the disorder appears before the age of 40.  Medical conditions, such as hypertension, as well as family history are risk factors for glaucoma, which is why it is most often seen in older individuals.  When it strikes at a younger age, family history usually plays a role.

Primary Congenital Glaucoma: Hereditary

The term primary congenital glaucoma is used when the disorder appears before the age of five.  In these cases, a child is usually born with structural abnormalities in the eye that prevent proper fluid drainage.