Help with a sentence?

[Jacob Baltuch]

Aplogies for the following elementary question. The Sanskrit
list if of course the place for such queries, and I have asked
the question there, but received no answer. Maybe my question
was swamped by the noise of more interesting debates.
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In a textbook I found the sentence:
``kah khalu pati-patnyoor madhyee yad vrttam tat sarvam jaanaati?
svasya maataa-pitroor api sarvam caritram jJaatum na zakyam''
and I don't know what to make of ``svasya''. I wanna translate
``who indeed knows all that which went on between husband and
wife? the whole life of one's father and mother even it is
impossible to know''... but for that I should have expected
``svayoor maataa-pitroor api''. Can you help? Thanks. And Happy
New Year to all.