However, after social differences between mothers were taken into account there was only a 30 per cent difference. (telegraph.co.uk)
Opportunity and achievement gaps based on race, class, language, or other social difference are being eliminated in excellent schools and systems. (nationalequityproject.org)
Further research is needed to explore whether similar processes may be at work in other animal societies, particularly those that are highly structured by social differences. (journals.plos.org)