Home grown I believe is actually talking about Grafting.
Grafting is a method where you take two shoots from two different plants. (I am not sure whether they both need to be females/males/or both) but you slice the stem of each shoot at an angle and join them together with a hormone, and stick them in your rockwool.
Now I am not entirely sure what happens next, I do not know if a new shoot sprouts up or what happens but one way or another the genetics get crossed and you have your new strain. I'm sure you can google "Grafting" and find out more about it.