So aside from small quirks all humans are the same? Depends on perspective. To the unacquainted outside observer, sure. All humans walk on two feet. All humans live in a social society. All humans become doltishly consumed by the pursuit of sex. (the previous three statements apply generally) But to a psychologist, certainly all humans are not the same otherwise the job of a psychologist would be obsolete. The variables studied can become evermore intricate, illuminating the differences between humans with increasing intensity. So yes, looking at it from a broad perspective, humans are all practically the same. But when we come down to the proper level of detail required to study human psychology, your insinuation that humans are all practically the same is stupefyingly idiotic.