What Causes Scientists to Reconsider the Nemesis Theory?

Extinctions on our planet occur periodically. The regularity of extinctions caused scientists to look for possible explanations. One of them is Nemesis theory and according to it, Nemesis is a dwarf red planet, which orbit lies behind the Oort cloud and stretches behind the icy objects from the Oort cloud, causing the great disturbances in their movements through our Solar System.