Here are the possible solutions for not yours or theirs clue
Answer
Clue
Relevancy
mine
Clue
Not yours or theirs
Definition
to dig for valuable materials
nontransferable
Clue
Yours and yours only
Definition
not transferable
reefermadness
Clue
1930s anti-marijuana propaganda film that ends with the principal of a school saying, "The next tragedy may be that of your daughter...or your son...or yours or yours..." [points at the camera] "... o
adopter
Clue
Person taking legal responsibility for a child not biologically theirs