Complex sentence: The Genain quadruplets (born in 1930) are a set of identical quadruplet sisters notable for all having schizophrenia, suggesting a large genetic component to the cause of the disease.
Split into simpler sentences: The Genain quadruplets (born in 1930) are a set of identical quadruplet sisters. All four developed schizophrenia, suggesting a large genetic component to the cause of the disease.