Additional anecdata, and also a woman:

I do this for any or all of the following reasons:

* (culture) it is polite to leave something for the next person

* (I have roommates) I don't want to be the last person who finished something. I would be obliged to replace it.

For the typical girl thing, I haven't seen this behavior in real life with my family members or friends. I have heard of the concept on social media.

I do this, but it's not really about if it's "gross" to eat a whole bag or not. I don't feel like doing that anyway. It's mostly that if you share food, I think it's considerate to leave one if there's more than one left. Someone else might be having a really bad day, but a small consolation could be that they didn't get home to discover there aren't any cookies left.

I do it to avoid being blamed, I don't know what you're on about. I've never cared that much about the semantics of how many cookies I ate (then again, I'm on hacker news so I might not be the best representation of the female populace)

I tend to do the cookie baking, so it'd be a little silly for me to be mad over someone eating them.

And for what it's worth, no one deserves blame for their cookie habits.

Gotta maintain that figure if you ever wanna escape poverty. Reba McEntire wrote a whole song about it.

(joking, but not nearly as much as I wish I was)