This is my comment for BBC messageboard in case of the strange rumour that Carlos in fact should be son of Alban Berg.

I researched about Carlos for many years, got a lot of intimate material and spoke to many people, also relatives and near friends of Carlos. I did not find any hint in case of Berg. I think its only a rumour. Because many people in Austria did not love Erich Kleiber, they would very much prefer Carlos to be a son of Berg. I also read letters of Erich to his wife from 1926-1929, seemed to be a very happy marriage with her, letters are full of love. And people who knew them well told me how much Ruth Kleiber adored her husband. And Berg felt in love deeply with another woman in that time, Hanna Fuchs, sister of Franz Werfel, new published letters confirm whow deep this relation was. As it is diskussed in my German Kleiber-Biografie I think on pictures, especially from the young EK there are similarities to CK, also in case of pictures of the elder CK with EK. And: Nobody before thought about Carlos` mother and nobody compared her looking with that of CK. The similarities in face are obvious. And she was much taller than EK ...