Genitive case is confusing me. Let's consider the following two sentences:
Das ist das Auto deiner Schwester.
Das ist die Frau, deren Bruder krank ist
In the first sentence, it is taking the gender of the second word,
Schwester to write
deiner. If it took first one,
Auto, it would have been
In the second sentence, it is taking the gender of the first word,
Frau to write
deren. If it had taken the second one,
Bruder, it would have been
There seems to be no consistency in which word is used, to determine what pronoun to use. Am I missing a rule??