The gender of shapes

I was staring at a plaid jacket and wandering about squares when I realized it's partially about sex. It's always about sex. Just ask Bill Shatner. He doesn't climb a mountain, he makes love to a mountain. *(I apologize in advance. It will be stuck in your head for at least one month.)

What does plaid make you think of? (Not rhetorical).

The first thing that comes to mind is men. It has a rugged quality to it. Of course, now it's popular among men and women, (I happen to be wearing a plaid jacket this very moment), but if we had to go through and deem every pattern as either male or female, plaid would be male.
1970's ad for slacks

What about polka dots? It was a yellow polka dot bikini that she wore. The bow on mini mouse: polka dots. It's a feminine pattern. Interestingly enough, it's faded almost entirely out of the world of fashion lately, (for all that I know, at least).

Plaid = squares, polka dots = circles.
Plaid is male. Polka dots are female.

Draw a circle and a square on a sheet of paper. Show this paper to someone and ask them to identify one as male and the other as female. I am confident they would choose the square as male and the circle as female 9 times out of 10. It's instinctual.

Why?

Some people suggest it's because men tend to be more square shaped and women more round. Fair enough, but I think there's more to it.

Pipes and drains are circular. The fastest rivers are those whose bed is shaped like a perfect semi-circle. Hoses and vacuum tubes act as passageways for water and air. Generally, anything that something else moves through is circular. It's one of the things circles are designed for.

Anatomically and sexually speaking, isn't the man the "mover" and the woman "that which something moves in"?

Perhaps somehow, on the palest levels of the collective subconscious, we feel this without knowing it, and that's why we identify the square as male and the circle as female, and that's why plaid is masculine and polka dots are feminine.
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EDIT: I just re-watched the linked video and realized that Shatner happens to be wearing a sort of red plaid during that video. Weird. I didn't even plan that. This proves my theory that everything can be related back to that man.