You may do it by randomizing the ***shape keys*** values using a script.
[![enter image description here][1]][1]

Create some shapekeys for your model (change head, body and other body parts parameters).
[![enter image description here][2]][2]

In ***Text Editor*** window click on ***New*** button, copy the script from here: http://blender.stackexchange.com/questions/40382/how-to-set-a-random-value-for-multiple-shape-keys and paste it to the editor window. As you can see, all the shapekeys values changed randomly.
[![enter image description here][3]][3]
[![enter image description here][4]][4]

Go to ***User Preferences*** (<kbd>Ctrl</kbd>+<kbd>Alt</kbd>+<kbd>U</kbd>) and enable the ***Corrective Shape*** keys addon.
[![enter image description here][5]][5]


In the Shape Keys panel click on the arrow icon and choose ***create duplicate for editing*** option. Now you have new unique mesh. You can create many of them very fast. The more shapekeys you have, the more combinations are there. Good luck :).   
[![enter image description here][6]][6]


  [1]: https://i.sstatic.net/F9CwU.gif
  [2]: https://i.sstatic.net/SIMgX.jpg
  [3]: https://i.sstatic.net/0xvQ5.jpg
  [4]: https://i.sstatic.net/brWWR.jpg
  [5]: https://i.sstatic.net/yroVX.jpg
  [6]: https://i.sstatic.net/qIEWK.jpg