Abigail keeps sending in great questions!
Her latest:

Shalom, it is my understanding that the father (or oldest male?) in the house prays the Aaronic blessing over the family and others in the home on Erev Shabbat. Correct?
In the absence of an adult male, would the mother (oldest woman?) then pray it instead? Or is it skipped?

Our answer:

This Aaronic blessing is “officially” recited by the descendants of Aaron, the “Kohanim,” of which there are still many today! From my layman’s educated guess, about ten percent of all Jews are Kohanim (plural of Kohen, or Cohen). In modern Israel it is recited every day in the morning prayers. Elsewhere in Jewish communities, it is only recited on holidays. That’s another perk of living in Israel:-)

There are many other times when these verses are said, not necessarily by Kohanim.

First of all, every morning it is part of the preparatory prayers (see this lesson, where Gidon teaches that prayer).

Recently, I have noticed a new tradition, that Kohanim will gather around the newborn baby at a circumcision ceremony at its conclusion, and pray this prayer over the baby.

And of course, it is a very old tradition for the father or both parents to pray this blessing over each of the family’s children upon returning to the home from Shabbat evening prayers.

In our house, my wife and I both recite this blessing, in some houses (most?) it is just the father.

When I was not married and not living in my parents’ home, I would often eat meals with other singles, and in such a case, no one would say this prayer, I have never seen anyone blessing EVERYONE present, including guests, but really, anything goes:-)