It all can depend on what order siblings are in your family too.  Younger siblings tend to pick things up much faster because they copy and mimick their older siblings.  I have two under two’s here that can talk till they drop---and I have to tune out sometimes as it is the only way to get some peace around here.  (Which supports Lynn’T’s post under Macarena’s post about her baby possibly being deaf).  They also argue and squabble like the older ones too.  They learned it as a side line to actually picking up words and learning to talk from the older ones.  :)