I feel stupid asking this, but if youre running packs in series what are the negative consequences of using say 12 matched cells and 4 cells of a different make?

Will they blow up or something, I'm just really interested in seeing what 16 cells will do in my jet villain IV and I dont feel like driving a total of 140 miles to get more matched cells, when I have many packs laying around.

If it'll just most likely kill the inferior cells, then I dont care, it's worth it for the experiment but I dont want to ruin my boat, my 12 good cells, or the motor. To give some info my 12 cells are 2400 mah and the unmatched packs range from 1200 to 1400 mah, of different brands.

p.s. my setup can handle 16 cells, limited only by the motor.