Questions & Answers about To jest mój brat, czyli twój wujek.
Why is it mój brat (Nominative) instead of moim bratem (Instrumental) if we are stating someone's family relation?
You use the Instrumental case when describing someone's relation or profession using a personal pronoun, like On jest moim bratem (He is my brother). However, when you use the pointing phrase To jest... (This is...), Polish requires the basic Nominative case. This is a common rule to remember: To jest + Nominative.
What exactly is the role of czyli in this sentence?
Czyli translates to "that is", "in other words", or "meaning". It's a very common conjunction used to clarify, summarize, or rephrase the thing you just said. Here, it simply equates "my brother" with "your uncle" to explain the family tree.
Is the comma before czyli required?
Yes! Polish punctuation rules are quite strict about commas before certain conjunctions. You must always place a comma before czyli when it introduces a clarification or explanation like it does in this sentence.
Does the phrase after czyli have to match the grammatical case of the phrase before it?
Yes, it does. Because czyli is just re-identifying the exact same person, both descriptions stay in the same case. Since mój brat is in the Nominative case here, twój wujek must also be in the Nominative case.