How to determine if rocks are co-genetic?

https://en.wiktionary.org/wiki/cogenetic

did they all come from the same outcrop?(location on a geologic MAP)

Are they sedimentary or not?

"Having a bunch of rocks" is hardly accuracy in action here.
Tell us what theyve got in common


"co-genetic" is not a term thats in common use in geology, because part of the identification chain would already include working out the detailed data on what makes each outcrop unique in time and genesis.

For three igneous thin sections/hand specimens I have, I have to determine if they are related by some processes of magmatic differentiation. I'm not sure how I would figure this out? This is from lab work.

look at the thin sections. Do you see any feldspathoids or plagioclases??

You can use these to determine temperature differentiation.
Also, structural features.

Is this petrologyor economic geology??