I don't know why you're describing my mother as masculine but she apologises

So... chivalry?

I am of the belief that masculinity and femininity are social constructs, but that they are also not only social constructs and nothing else.

There's a lot of interesting work around this in studies/interpretations around Jungian archetypes. Structure, courage, strength, independence, rationality, leadership and assertiveness are virtues/traits that are generally (but not exclusively) associated to masculinity. Charm, empathy, collaboration, compassion, humility, intuition, sensitivity, beauty, style and introspection are typically associated to the feminine (but not exclusively).

In essence, i read somewhere (i think an old Tarot book iirc), that which is masculine imposes and confronts, while that which is feminine contains and nurtures. Seemed to make sense, to me anyway.

edit: A quick clarification is that these are typically, at least under the Jungian and broad oriental notions, not considered mutually excluding opposites, just polarizing forces. Like broad, vague and intersecting maps of associations. The Ying Yang symbol illustrates this well. Each side has a part of the other side within itself, and each one needs the other in order to exist.