Most universities don't let random students (foreign or domestic) come study for free. You either have to be really good or pay your way. In all seriousness th

Most universities don't let random students (foreign or domestic) come study for free. You either have to be really good or pay your way. In all seriousness though, I can only think of one or two occasions personally where citizenship had an effect on a PhD admit decision, and in those cases the source of funding and external politics were the deciding factors.