Yes it is - gender is entirely a social construct. I didn't realize that's what you were getting at because it's so patently and obviously the case. Sex is biological, but sex and gender are not the same thing. Many cultures have 3 or 5 genders, and the norms of gender differ in different cultures and at different periods of time which proves that there aren't really any constructs of gender that are immutable that don't have to do with reproduction/nursing, etc. In some cultures, women are the head of household and in some its men. Some women do most of the farming, and in others it's men. Some cultures pass down land or family name through the male line and some through the female line. Prior to 4 BC, Egyptian women went into the marketplace to transact business and legal matters and men stayed home and did the weaving.

Good heavens, I would have thought in this day and age I wouldn't have to clarify that sex and gender are not the same thing. Great story prompt though, so thanks for that.