The exact cause of amyotrophic lateral sclerosis (ALS) is not fully understood, but it can occur sporadically or be inherited. In most cases, ALS develops randomly without a clear cause (sporadic ALS), while about 5-10% of cases are hereditary (familial ALS), caused by genetic mutations. Risk factors include age (typically developing between ages 40-70), gender (slightly more common in men), and potentially environmental factors, although these are still under investigation.