A representative survey conducted by University of Konstanz and presented by Integration Minister Bilkay Öney (SPD) on 28 November shows that about one third among the grandchildren of Turkish and Italian immigrants in Germany does not have German citizenship and is not interested in acquiring it. Reasons cited by those asked in the survey include that they would still be treated as foreigners even with a German passport, that they do not feel to be Germans or that they do not want to lose their Turkish citizenship (Germany allows that Italians and other EU citizens can retain their citizenship of origin when they naturalise). Only since 2014 can children of foreign parents who acquire German citizenship at birth if a parent has lived there for eight years and has a permanent residence permit retain both citizenships beyond age 23 if they themselves have lived in Germany for eight years or have attended school there for at least six years. 

read the article in Schwäbische.de (in German)