When should I use dative instead of genitive? Are they interchangeable? Is it okay to use "von"?1 answer
Genitive is used for showing possession and other times with specific prepositions.
Dative is used with certain sentences and prepositions like "von" "zu".
They are not the same thing but I can understand why this question came out. Sometimes you see a dative instead of a genitive. Let's say that that's not proper German. Meaning that you should definitely avoid it if you want to write an essay or in general in good and proper written German.
This doesn't mean that you don't hear native speakers using it while speaking. It happens. Yet, it's not good German.
Schreiben ist Teil meiner Routine Writing is part of my routine
Schreiben ist Teil von meiner Routine Writing is part of my routine
They mean the same thing and you might hear both but the first one is the correct one because it is a possession.
In some cases it might convey slightly different meaning:
Ich bin ein Vater der fünf Töchter I'm a father of five children
Ich bin ein Vater von fünf Töchtern I'm a father of five children
They can be translated in the same way but the meaning is quite different and the first sentence is quite weird.
The first sentence means that I'm the five children's father. Which sounds a little off to me. The second one simply means "I'm a father with five children".
So, despite there are basic rules described at the beginning always be careful that there are exceptions and that context is the key.