But some alumni of Britain's Deobandi institutions do advocate self-segregation by Muslims, especially where local indigenous culture is dominated by alcohol and drugs.

ECONOMIST: Islam in Britain and South Asia

"I think it's fair to say that the Web has great potential to at least mitigate everyday tendencies towards self-segregation and social exclusion, " Kaufman said.

CNN: Does class decide online social networks?

Is that a result of the self-segregation social entrepreneurs assign themselves?

FORBES: Social Start-Ups Are For Technology, Not Transformation

But simpler, more open networks also permit self-segregation.

ECONOMIST: E-communication and society

Jason Kaufman, a research science fellow with the Berkman Center for Internet and Society at Harvard University, examined the Facebook profiles of a group of college students over four years and found that even within Facebook, there's evidence of self-segregation.

CNN: Does class decide online social networks?