Complex sentence: While reviewing pictures from the wedding she missed, Michael's mother is shocked to discover that she knows Patricia's father; he is also Michael's father, the result of a brief tryst between the two many years before.
Split into simpler sentences: While reviewing pictures from the wedding, Michael's mother is shocked to discover that she knows Patricia's father. Even more shocking is the revelation that Patricia's father is also Michael's father, the result of a tryst between the two many years before.