is it because I am German?

It is totally obvious to me to pronounce and to hear the difference of aspirated vs. non-aspirated plosives: p-b, t-d, k-g. However for the affricates I can not hear the difference between aspirated and non-aspirated ones: [in Pinyin notation] c-z, ch-zh, q-j. Admittedly, it is even hard for me to tell the difference between the alveolar affricates c-z and the alveolar-palates ones: q-j. However, those are quite important in Chinese and I would really like pronounce and distinguish them well. Admittedly, q-j can be told from c-z by context, but the distinction between q and j and between c and z is quite important.
Hello my linguist friends, who wants to enlighten me?