Robbers Cave

Muzafer Sherif made a concerted effort to recruit Caucasian boys who were approximately 11-12 years old that came from similar backgrounds (e.g., middle-class Protestant families). All the boys in the study had above-average IQ, and were similar in terms of their athleticism, popularity outside of camp, and previous camp experience.
Why do you think Muzafer Sherif made such an effort to have the participants be so similar with each other?
What did the Robbers Cave study reveal about conflict and peacemaking? Does this study show parallels with anything in current world news?

https://www.youtube.com/watch?v=8PRuxMprSDQ&t=2s