Learn Hardcore Polish: Mój brat woli koszykówkę, a siostra woli siatkówkę. - My brother prefers basketball, and my sister prefers volleyball.

In Polish you don’t have to repeat a possessive adjective (mój / moja / moje, etc.) when it’s clear from context that you’re still talking about “my” family members.

Mój brat = my brother
(moja) siostra = (my) sister

The owner (the speaker: “my”) is already established in the first part, so in everyday speech and writing it’s very natural to drop moja in the second part:

Mój brat woli koszykówkę, a (moja) siostra woli siatkówkę.

Both are correct, but saying moja siostra here is a bit heavier and more explicit than most natives would use in a simple sentence like this.

Why do koszykówkę and siatkówkę end in -ę instead of -a?

The base (dictionary) forms are:

koszykówka – basketball
siatkówka – volleyball

In the sentence they are direct objects of the verb woleć (to prefer), so they must be in the accusative case (biernik).

For most feminine nouns ending in -a, the accusative singular ends in -ę:

nominative (dictionary form): koszykówka → accusative: koszykówkę
nominative: siatkówka → accusative: siatkówkę

So:

Mój brat woli koszykówkę. – My brother prefers basketball.
Siostra woli siatkówkę. – (My) sister prefers volleyball.

Which case does the verb woleć take for its object?

Woleć (to prefer) takes the accusative case for its direct object, just like lubić (to like):

wolę kawę – I prefer coffee
wolisz herbatę – you prefer tea
woli koszykówkę – he / she prefers basketball

So whenever you say what someone prefers, that thing goes into the accusative.

What is the difference between woleć and lubić?

Both are about liking something, but they’re used a bit differently:

lubić = to like (in general)
- Lubię koszykówkę. – I like basketball.
woleć = to prefer (A over B)
- Wolę koszykówkę (od siatkówki). – I prefer basketball (to volleyball).

You can often use lubić alone, but woleć almost always implies a comparison, even if the “than X” part is not actually said.

In the sentence:

Mój brat woli koszykówkę, a siostra woli siatkówkę.

we’re clearly comparing two sports, so woleć fits perfectly.

Why is the conjunction a used here and not i or ale?

Polish has several “and/and-but” words:

i – simple and, just adding things:
- Mam brata i siostrę. – I have a brother and a sister.
a – contrasts or separates, often and / whereas:
- Mój brat woli koszykówkę, a siostra woli siatkówkę.
  = My brother prefers basketball, whereas my sister prefers volleyball.
ale – but, stronger contrast / opposition:
- Mój brat woli koszykówkę, ale czasem gra w siatkówkę.
  = My brother prefers basketball, but sometimes plays volleyball.

In your sentence a is used because we are contrasting two people’s preferences in a neutral way: brother vs sister.

Why is there a comma before a?

Polish punctuation normally requires a comma before most conjunctions that connect two full clauses (each with its own subject and verb), including a, ale, bo, etc.

Here you have two clauses:

Mój brat woli koszykówkę
siostra woli siatkówkę

They are joined by a, so Polish puts a comma:

Mój brat woli koszykówkę, a siostra woli siatkówkę.

Could I say Mój brat woli koszykówkę, a siostra siatkówkę and drop the second woleć?

Yes, that is possible and natural in Polish:

Mój brat woli koszykówkę, a siostra siatkówkę.

The second woleć is understood from context and can be omitted to avoid repetition. Both versions are correct:

with repetition (more explicit):
Mój brat woli koszykówkę, a siostra woli siatkówkę.
without repetition (more compact):
Mój brat woli koszykówkę, a siostra siatkówkę.

Can the word order be changed, for example Siostra woli siatkówkę, a mój brat woli koszykówkę?

Yes. Polish word order is more flexible than English. Both are fine:

Mój brat woli koszykówkę, a siostra woli siatkówkę.
Siostra woli siatkówkę, a mój brat woli koszykówkę.

The meaning is the same; you just change which part you present first. The usual neutral pattern is [subject] – [verb] – [object], as in the original sentence, but you can often reorder parts for emphasis or style while keeping the same grammar.

How is woleć conjugated in the present tense?

Woleć (to prefer) is a regular -eć verb, but note the change in the stem consonant (l → l):

ja wolę – I prefer
ty wolisz – you (sg.) prefer
on / ona / ono woli – he / she / it prefers
my wolimy – we prefer
wy wolicie – you (pl.) prefer
oni / one wolą – they prefer

In the sentence:

Mój brat woli koszykówkę – third person singular
siostra woli siatkówkę – also third person singular

Why is it mój with brat, but would be moja with siostra?

Possessive adjectives agree with the gender of the noun:

mój brat – my brother (brat is masculine)
moja siostra – my sister (siostra is feminine)
moje dziecko – my child (dziecko is neuter)

So:

mój
- masculine noun: mój brat, mój kolega
moja
- feminine noun: moja siostra, moja koleżanka
moje
- neuter noun: moje dziecko, moje mieszkanie

In the sentence, we see just mój brat, but if you included it, you’d say moja siostra.

How do you pronounce siostra, koszykówkę, and siatkówkę?

Approximate English-like guidance (not exact IPA):

siostra – shyo-stra
- si before a vowel is like soft sh
  - y: śo ≈ shyo
koszykówkę – koh-shi-KOOV-keh
- sz = sh
- ó = same sound as u (oo in food)
- kę at the end: ę is a nasal vowel; in everyday speech it often sounds close to -e with a hint of -n before consonants, so you may hear something like -kev / -ke.
siatkówkę – shyat-KOOV-keh
- sia ≈ shya
- again ó = u sound, and -kę similar to -kę in koszykówkę.

Perfect Polish pronunciation takes practice, but if you aim for these approximations, you’ll be understandable.

Could I say this with lubić instead of woleć?

You can, but the nuance changes:

Mój brat lubi koszykówkę, a siostra lubi siatkówkę.
= My brother likes basketball, and my sister likes volleyball.

This simply states what they like, without directly comparing the two sports.

The original with woleć highlights preference (A rather than B). So:

woleć – emphasizes choice / preference
lubić – neutral liking, no explicit comparison

Both are grammatically correct, but they don’t say exactly the same thing.