Legal Question in Real Estate Law in California

As you apparently expect, the three would own 50%-25%-25%.......assuming there are no unusual terms in the inheritance itself or in the sister's quitclaim deed.

It would be necessary to see the actual deeds. If your statements are an accurate descrioption of what the deeds actually say, the brother who received the quitclaim owns 50%, and the other two children own 25% each. To verify this a chain of title investigation is required. Is the property still in your parents name? Was it probated? If so what was title like before the quitclaim deed was recorded? Exactly whose name was the quitclaim indicating as the transferee?

It would have been cleaner if the departing sister had used a grant deed, but I agree with the previous answers.