Perhaps one the most spectacular advances in the last two decades of Astronomy research has been the finding that central supermassive black holes (SMBHs) not only do exist but also appear to be ubiquitous in galaxies. In fact, it would even seem that SMBHs "know" in which galaxy they live, as their mass happens to be always around 0.2% that of their hosts. Such a coincidence is quite puzzling considering that SMBHs, although several million to billions times more massive than the Sun, can only directly affect the motions of gas and stars at the very center of galaxies. How could galaxies form and evolve through Cosmic time and arrive always at the same SMBH mass budget, in particular, considering how different formation channels may have led systems as different as Spiral and Elliptical galaxies? I will show how astronomers are trying to solve such a complicated puzzle.