There is no maybe, every study that has ever looked into this since the dawn of science has confirmed this.
Indeed. For example, even the ancient Greeks and Romans knew perfectly well that these uncouth blue-eyed barbarians from the North were obviously dumber than the glorious Mediterranean master race.
Hell you don't even have to ask science, every average Joe on the street knows this already from life experience.
Ask "average Joe on the street" what he thinks about evolution.