"We share the same biology, regardless of.."

  When being a child and a school-girl i've always considered people to be so alike. I was somehow taught that they were, or maybe i thought i knew it... Now when i meet other people i undersand, that sometimes it is right, and sometimes it is strikigly the opposite. The point is it does never depend on their culture or language, though it might seem at first such things should make people closer. They do not. Why?... And what does then?