(I am not a teacher)
This expression is often used in a negative context. It is another way to say "the product of someone's actions".
"I got fired from my job yesterday. I'm sure it was my co-worker's doing." (my co-worker caused my firing)
"Mom, my bank account had an extra $500 in it this morning. Was that your doing?" (Not exactly a negative, but expressing suspicion.)
Student or Learner