Brothers Or Brother's

Are they brothers? What is grammatically correct? 3

You really should know this. I thought it was the last one, but it felt bad when I wrote it.

Also, in which category can I ask this question for reference?

Thanks in advance! Kiss kiss

update

Sorry for the lack of context, I can't even think about it today.

Siblings should not fight because this is the first rule. I realized they were brothers because it didn't make sense, because brothers shouldn't fight.

The plural of brother is brother: I have two brothers.

To show ownership, this is the brother: this is my brother's car.

To indicate ownership of multiple items by multiple brothers, this brother is: Tse is my brother's car.

Brother, you don't have to fight ... OK.

My brother's car broke down. Apostrophe turned my brother's car around.

The sister planes won the race. The quotes used to kick the boat belong to more than one brother.

Brothers Or Brother's

I have a brother. My sister's eyes are the same color as mine.
I have two brothers. My brothers' eyes are like mine.
(My brother's eyes will be fine too. But I like the extra for clarification).
Probably the best place to answer this kind of question is words and word play.
Depending on the context. Brother means many brothers. Brothers means brother's property ... that is, my brother's car.
Hello Nina, and I think you should stay with your brother, and the category is education and reference.
I wish you good luck
Brothers and sisters
Plural
Adding s means your brother's car and so on.