Analysis by 23andme identified my maternal haplogroup as H1 and my son's as H17. Their explanation is that his analysis is more detailed than mine, not inconsistent. Looking at phylotree, that doesn't make sense to me. H17 is a completely different subclade, not a "child" of H1. If it's that easy to mutate from one subclade to another in a generation, maternal haplogroup would be meaningless for tracing ancestry. Or am I totally missing something? Input appreciated!