I am so sorry for the loss you and your wife have just experienced. A lot of people seem to think that me father does not grieve a child that was not yet born. But miscarriage is a loss for both the mother and father. That child held all your hopes and dreams for a future as a family of three and now those dreams are gone..
We know that due to WTS teachings the advancment of social interactions is behind the rest of the world. Remeber much of the thinking of the GB is that of men born the first half of the 1900s and they have been insulated from the real world for decades. This is why JWs are rather backwards and is one reason why there is such a thirst for knowledge when people leave. They feel like they need to play catch-up. So your family might be thinking somewhere along these lines. That the father does not grieve.
or is this barbaric religion so powerful that it can change a persons personality that much?Yes the WTS can and does have this kind of control over its members