As far as i am concerned, the blepharitis is not genetic. The blepharitis is characterized by an inflammation of the eyelids, causing itchy and red eyelids. And I think the reasons that can give rise to it are almost because of the living environment, just like bacteria usually found on the skin, and your unhealthy lifestyle, which may also cause this kind of diease. It is said that blepharitis is not inherit from parents. So, your living environment and lifestyle are more important than genetic to get blepharitis. It can be controlled with proper eyelid hygiene, but if you left untreated, it can progress into a more serious condition like injury to your eye's tissue, making eyelash fall off and enter into the eye which can cause conjunctivitis. Thus you'd better take some measures as soon as possible when you get it.