Questions & Answers about Это мать, сын которой жил здесь.
Why is it которой (feminine) when the noun next to it is сын (masculine)?
When used in the Genitive case to mean 'whose', the relative pronoun который acts like 'of whom'. It gets its gender and number from the noun it refers back to in the first part of the sentence. Here, it refers back to мать (mother), which is feminine. Therefore, we use the feminine Genitive form, которой.
Why is the word order сын которой instead of которой сын?
When expressing 'whose' using the Genitive case of который, Russian usually puts the possessed object (сын) right before the 'whose' word (которой). If you translate it literally in your head as 'the son of whom', the Russian word order makes perfect sense!
Why is the past tense verb жил masculine if the sentence is about a mother?
The sentence is split into two clauses. In the second part (the relative clause), the subject doing the living is the son (сын), not the mother (мать). Because сын is a masculine noun, its past tense verb must also be masculine (жил).
Why is the comma placed before сын and not before которой?
In Russian, you must always use a comma to separate a main clause (Это мать) from a relative clause (the part that gives more information about the noun). The comma marks the exact beginning of the new clause. Since сын is the first word of that descriptive clause, the comma goes right before it.