Berten et al. BMC Public Health 2012, 12:215 http://www.biomedcentral.com/1471-2458/12/215 students, while these effects were absent or negligible in the sample of migrant students. We explained this find- ing by referring to the buffering effect of religion in the relationship between education type and substance use. Students from Islamic background make out the major- ity in the group of students from another ethnic back- ground, and these students not only profess their religion in a much more conscious way, they are also the product of families and cultures that put more emphasis on religious values such as for instance absti- nence than their native Belgian counterparts [47]. A somewhat remarkable finding of our study was the positive association between parents’ educational level and alcohol use. Students from families where parents are highly educated used more alcohol in the last month, independent of the students’ educational level. Such a finding was not found for cannabis use. A possi- ble explanation may be that students from high SES backgrounds simply have a more attractive financial background, allowing these youngsters to buy alcohol- related products [20,48-50]. For cannabis on the other hand, the financial strength of students’ background may be of minor importance. For instance, cannabis is often consumed and shared in larger groups of teens, and especially the amount of cannabis needed to get high is much cheaper in price than the amount of alco- hol needed to get drunk. Furthermore, cannabis is leg- ally prohibited, and is dependent on having the ‘right’ connections or resources to buy these products, and these connections may be much less dependent on the familial SES background of these students. Other expla- nations are however possible and further research is necessarily to explain these results. This study suffered from a few limitations. A first lim- itation is that this study is based on self-reports, making it plausible that the these self-reports are biased by social desirability pressures. A second limitation relates to the recall period in the study (i.e. incidence rates of alcohol and cannabis in the last month). Since students may experience difficulties in remembering exactly how many times they used these substances during the last 30 days, it may be more accurate to focus on shorter recall periods. Also, the analyses presented here are based on outcomes that measure whether the adoles- cents consumed alcohol or drugs more than three times in the last month, and thus problematic drinking beha- vior is not really measured. Thus, it may be that the dif- ferences between the educational tracks, but also between the migrant and native groups, become even more pronounced when using measures of binge drink- ing, alcohol intoxication, etc. Because of the restrictions of our alcohol outcomes, our study did not let us to conclude that the so typical ‘reversed pattern’ -moderate use of alcohol in higher socio-economic groups, less Page 7 of 9 frequent but more problematic alcohol use in lower socio-economic groups- is also observed in adolescence. However, the literature indicates that once teenagers grow older and enter adulthood, such a pattern may start to unfold [11-13]. Conclusion Consistent with equalization theory, this study found lit- tle effects of parental SES markers on students’ sub- stance use, and where such effects existed they marked social gradients in a reversed pattern. Following West [21,22], adolescence is characterized by a “process of equalization”, but only for what concerns their familial socio-economic background. Our study showed, how- ever, that when using education type as a proxy of one’s individual socio-economic status, clear differences per- sist among native Belgians in different educational tracks. Thus, structural causes of inequalities are still prevalent, but they work via the schools’ students are ascribed to. For future research this means that it may no longer be sufficient to determine adolescents’ social position merely on parental SES indicators. Rather, it is required to chart students’ own social position as well, for which education type can be used as a proxy. Other- wise, researchers are blind for the diversity and SES based social stratification that still persists within Bel- gian, but also other European, schools. Acknowledgements This study was made possible by the financial support of the Ministry of the Flemish Community - Department of Culture, Youth, Sport and Media. Author details 1Department of Social Welfare Studies, H. Dunantlaan 2, 9000 Ghent, Belgium. 2Department of Experimental Clinical and Health Psychology, H. Dunantlaan 2, 9000 Ghent, Belgium. Authors’ contributions HB conducted all statistical analyses, wrote, and coordinated the paper. DC co-wrote the manuscript, RB provided statistical support, and NC was co- responsible for the data collection and supervision of the Brussels youth monitor and provided theoretical additions and other comments to the manuscript. All authors commented on drafts, have read the revised manuscript, and have approved the final version. Competing interests The authors declare that they have no competing interests. Received: 16 December 2011 Accepted: 20 March 2012 Published: 20 March 2012 References 1. 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