I just posted a new thread on MtDNA inheritance because I recently read that MtDNA can be passed down from the paternal line! That is significant if true. It conflicts with everything that we are told on these sites. In my case, it makes sense. My eight low resolution MtDNA matches are mostly Dutch and Belgian. My mother's family line goes back to Scotland, with little chance of so-called "unannounced adoptions". My paternal grandmother was Dutch.http://www.vetscite.org/publish/items/000765/index.html
My wife's numerous MtDNA DNA matches would make more sense if there was a paternal inheritance.
By the way, there is a maternal component in Y-DNA, but the DNA experts say it has no impact of Y-DNA results or interpretation.