In this question, the user quoted an example sentence and asked
How does jemands decline in genitive form?
I have asked for clarifications in the comments. However, the OP later posted an answer that indicated that their actual question seemed to be
Why does jemands decline in genitive form?
I am not certain, how to proceed here:
Option 1 Edit the question according to OP's answer and to the price that other answers become invalid. However, one might argue, the other posters could/should have asked/waited for OP's clarification.
Option 2 Leave the question as it is and live with the discrepancy between OP's question and answer and wait for more "unclear what you're asking" close votes.
Option 3 Something else?