Approximately 5-10% of all cases of ALS are inherited (passed from one generation to the next).
In 20% of the inherited type the genetic mutation is known (superoxide dismutase-1) and it is inherited from generation to generation in an '
autosomalPolycystic kidney disease dominant' fashion - this means that, in this rare form of ALS, if one parent is affected, there is a 50% chance that a child will be affected.
in the other 80% (of inherited ALS) the cause is unknown, and therefore the inheritance pattern in unknown, although a lot of research is being done in this area.
If only one family member is affected, the odds are very stacked in your favor that the disease will not be inherited