That's not true. In Illinois, Iowa, Michigan, Wis, Minn, Indiana and Missori, I have personally seen Sigma Chapters have close relationships with the Betas and Gammas. Mostly social stuff, not anything official or anything. At my undergrad chapter, we were really close, mainly because we were in the same boat, a small population of Black and Latino students from inner cities who were now at a very large predomiately white university. So the bond came naturally.