[Maru]

Originally Posted by Jack_

I'm not sure I agree with that, with the exception of cleavage (which varies a hell of a lot) how can you perceive one's sex without seeing what's underneath their trousers?

Look up skeletal/anatomy studies for portraiture/figure drawing. There are courses dedicated to (edit) dealing with proportional differences between a man and woman. Here's one such summary...

Drawing the Human Body: 5 Tips for Drawing the Torso
https://www.craftsy.com/art/article/...an-body-torso/

1. Know the differences between male and female torsos

Even though every individual has a uniquely shaped torso, there are some differences between male and female that apply in general:

• Males usually have longer torsos than females.
• Females have a bit more subcutaneous body fat. Accordingly, their shape is a rounder, and the muscles are a less defined.
• Female hips are wider, and their waist is usually a touch higher than in males.
• Shoulders are typically wider in males.
• Usually, the length of the spine is a bit shorter in a female than in a male.
• Male nipples are further apart than female nipples, which are more centered.

Human Anatomy Fundamentals: Advanced Body Proportions
https://design.tutsplus.com/articles...--vector-19869

Male vs. Female Proportions

Male and female proportions are so different that even a skeleton (or certain parts of it) betrays its sex. Bear in mind, however, that on a vertical axis there is no real difference: the joints don't move up or down. The variations are almost entirely on the horizontal axis, i.e. in the width of certain parts of the body. So how do we feminize or masculinize our basic figure? On the structural level we're still working on, there's actually just one big difference to master, and the rest are small helpful details.

The Shoulders/Hips Ratio

The primary difference is the relationship of shoulder width to hips. Women have a much broader pelvic bone than men, since they need to be able to bear and give birth to a child. This one, central fact has consequences throughout the body. It means that in women the hip line is the broadest part of the body, and a narrower waist appears by contrast, while in men the broadest part is the shoulder line, and the waist is hardly different from the hips. The overall female silhouette, then, is an hourglass as opposed to the male trapeze shown below.

Waist Line and Elbows

A woman's waist line is level with the belly button but a man's appears much lower. This makes the torso on a male look longer. This is worth remembering, as in my early years I drew equal-length torsos and same-level trouser lines for both sexes and wondered for a long time why the men didn't look right. Also, be careful not to align the elbows with this apparently lower waist! The reference for the elbow joint remains the belly button, so that unlike the female figure, if the impression we have of a man's waist is where his trousers start, the elbows will look much higher.