A facet of Gevurah is that of the feminine, as opposed to the masculine facet of Chesed.
Here one has to remember that in Kabbalah we cannot apply the same rigidity of thought as in biology.
What is of value for our purpose is the fact that the relationship between male and female is one of the most rudimentary ones in an extremely complex system of relations, human and otherwise.
It is human and beyond the human also in the way we divide the lines of the Sefirot into masculine and feminine forces, as influencing factors and those receiving influence, as right and left.
–Rabbi Adin Steinsaltz