A pronoun that modifies a gerund or a gerund phrase should appear in the possessive case (my, our, your, his, her, its, their).
Your modifies the gerund phrase being hit by lightning.
A noun that modifies a gerund or gerund phrase also must be in the possessive case: victim’s, birds’.
The possessive noun aristocracy’s modifies the gerund phrase exploiting the lower classes.
Exercises:
Pronoun case (such as I vs. me) 1
Pronoun case (such as I vs. me) 2
Pronoun case (such as I vs. me) 3
Pronoun case: review 1
Pronoun case: review 2
Related topic:
Possessive case of nouns