Earlier quoted context omitted.
I believe the level of inequality, and the level of social mobility (which is probably related to the magnitude of inequality), is more important than the existence of inequality.
Are you aware of any academic literature on the subject?
http://www.tandfonline.com/doi/abs/10.1080/13504850701720197
"We investigate the relationship between inequality and intergenerational mobility. Proxying fathers' earnings with using detailed occupational data, we find that sons who grew up in countries that were more unequal in the 1970s were less likely to have experienced social mobility by the late-1990s."