Pedigree

Look at this simple Pedigree... Indeed as a science students, this kind of chart is very common... but my rubbish mind keeps thinking more than that.

Why males=square and females=circle ??

Again, stereotyping..
Why can't males be circle and females be square?
Is it because a square looks fierce and spiky and a circle looks gentle and lovely?
Is it because males should have a squarish well-built body while females a nice curvatures?
Is it because males are suppose to be pointy and females a circular breast?
Is it because males are more straight to the "point" and females are more sensitive and prefer going "around" the bush?

Anyway, males=square and females=circle. Facts are facts. I am a square, and i hope to be a strong square. :P