Destiny in the Slaughterhouse (Chapter 7)

Destiny is pretty clear in Slaughterhouse, and there is a really strange part, when destiny appears. Has it never happened that you meet someone and kind of hate him but you don't know him enough like to do so, and then he appears to be related in some type? It has happened to me, and it has happened to Billy Pilgrim as well. It says 'They were, in fact, distant cousins, something they never found out.' (Chapter 7) What are the chances! Billy, a typical american studying optometry is related to the german kid who is guarding him at Dresde, being a war prisoner. Sad part is they never find out. It makes me doubt, though, that in the beggining of the book, the narrator sais most things are true. Is this the type of event that he means is not true? I find it very curious that Billy Pilgrim be related to a german kid, but I'm not the one writing the book. Perhaps it is true, and it is destiny and karma that Billy be guarded by his younger, german faraway cousin. Destiny is present in many other opportunities, maybe because Kurt Vonnegut has had his own experiences with it and reflects it in his writing.