No that is just, no just no. DNA is copied through cell reproduction where a cell splits to create more (growing for multi called organisms and asexual reproduction for single celled organisms) The mitochondria is an organelle that is the "power house" of the cell, the "digestive system".
In order for gas to leave a planet it needs to be hot enough and to overcome the planets gravity. The outer planets are colder and are very big compared to earth.
I'm not 100% sure, but I'd say the availability of vaccines and medicine.
