The voice acting in this game is sadly awful, main problem is that most sound wooden and stiff in their delivery of lines.
The actors sound like they are just reading directly from the script with no emotion or weight to their voice or sound like robots rather than humans and the ridged animation or motion capture doesn't help either as it leaves character models looking uncanny.
I would highly suggest that you bring the voice actors back in to redo their lines with more direction to put more emotion into their lines and age appropriate voices.