A woman I know mentioned that she is redeeming her firstborn son. This got me thinking. A Pidyon HaBen is mandated for the first male child to "open" the mother's womb. But whose Mitzvah is it?
The Pasuk is in the masculine. Does that mean it is the father's obligation? Do both parents share the obligation? EDIT (NEW SUB-QUESTION): Can the mother fulfill it if it's the father's responsibility?
There is a famous story that a famous rabbi (the GR"A, perhaps?) would, whenever he made the acquaintance of a Kohen, ask immediately for the opportunity to perform a Pidyon for himself (because of a safek that he felt existed in every Kohen's lineage).
Assuming the Safek was strong enough that the rabbi had reason to fear that his previous Pidyon(im) did not fulfill the Mitzvah, was it his responsibility to seek out more Kohanim to try again, or was that the sole responsibility of his father (or parents) to be fulfilled when he was a minor?