Brain aneurysms are focalized diseased blood vessels, often shaped like a balloon, which can rupture and cause bleeding in the brain. The presence of aneurysms is correlated with internal carotid artery (ICA) extracranial area variations and wider angles in the intracranial ICA terminus bifurcation. The goal of this thesis was to investigate a plausible hemodynamic stimulus that is statistically correlated with aneurysm presence by altering the morphological features in patient-specific geometries accordingly. The thesis is split into the following three chapters. To trust the numerical results, we first validate the solver for biomedical flows by employing the U.S Food and Drug Administration's benchmark for an idealized medical device [Stewart et al. 2012 Cardiovascular Engineering and Technology]. We obtained different results compared to previous studies, but offering reasonable explanations to the observed discrepancies, we put faith in our numerical solution. In the second chapter, a framework for objective manipulation of morphological features of intracranial arteries is presented and validated. As part of this work, an incremental improvement is made to the method for aneurysm removal presented in [Ford et al. 2009, British journal of radiology]. Finally, in the third chapter, we use the results from the previous two chapters to computationally investigate a plausible stimulus causing aneurysm initiation. Our results indicate that the plausible hemodynamic stimulus that statistically correlated with the presence of aneurysms is instable flow. That being said, in vitro/vivo studies are needed to confirm the mechanistic link between flow instabilities and the presence of aneurysms. Finally, we also present plausible explanations for why the leading theory of aneurysm initiation is an unlikely to occur in vivo.