This is a somewhat subjective matter.  Many of the qualities that make a face feminine are the same ones that make a face appear younger.  Feminine faces tend to have less "lines" than masculine ones; when drawing a feminine face it must be kept simple - too many lines (dimples, creases, wrinkles) make a face appear older, rugged, even manly.  When drawing a masculine face the opposite is true; simplified anime male faces often appear feminine to the western eye for this reason. 

Idyllic feminine faces generally tend to look younger (see neoteny) than idyllic masculine faces; they are generally smoother and rounder, more flesh and fat than muscle and bone.  Comparing idyllic feminine vs. masculine, the chin should be narrow rather than broad, the brow/forehead round rather than square.  Feminine noses tend to be shorter and less pronounced just as feminine eyes are larger and, again, younger in appearance.  The qualities that affect the face apply to the body as well.  Feminine features tends to be soft/smooth, round and delicate whereas hard/rough, square and rugged contours usually give impressions of masculinity.

A beard will do it every time :)

suggest you ask my ex wife haha :-)

In real life it's highly subjective, because we see movements and intentions more than bone structure. 

But in static 2d the main things are chin and brow.  Protruding or heavy chin and brow are definitely masculine characteristics.  The chin is what makes Vicky a man.

I would say: round, elipsoid shapes make female, rounded-block shapes make male. Especially in the lower jaw and forehead. And of course texture, hair, etc do make a difference.

And for texturing:  shorter, finer eyelashes and heavier brows. 

Quote - And for texturing:  shorter, finer eyelashes and heavier brows. 

For which gender? 

If it is for males, then you are generalizing.  Being male, I have long eyelashes; so does my 4 year old grandson.  It is a genetic trait.

Quote - Idyllic feminine faces generally tend to look younger (see neoteny) than idyllic masculine faces; they are generally smoother and rounder, more flesh and fat than muscle and bone.

For a good example, try to find pictures of female bodybuilders or physique competitors (ignore everything else, just pay attention to their faces) during a competition and off-season. With a few exceptions, during a competition, when they've pulled their body fat down to minimum levels and have little fluid their faces are typically described as "mannish" because they appear more angular, whereas the same woman off-season, when they have the same amnount of muscle but it's smoothed over with more normal levels of fat and fluid, can look much more stereotypically feminine. Obviously there's zero difference in bone structure, and the muscles in the face aren't any different.

Hi totally subjective opinion to follow:

IMPO it not just the face& jawline but  its something
I have dubbed her "HNR"
( head,neck, ratio)
,Long in length and medium to thin in girth,

To me, at least, a short thick neck can "man up" even the prettiest of faces and ruin her overall female beauty.

conversely a long graceful neck can make a healthy average to mediocre lady look quite pretty and feminine

the News/Entertainment media here in the New york market shows this definitively in their choices of women who they choose to put in on air
(not counting meteorologists).

Many of these long neck talking heads can barely articulate a sentence (see contessa brewer-NBC)
and some have faces that are average or below,
(to put it kindly) (see Lisa Huddy-FOX),

but they seem to have that correct head neck ration ratio.

Just my opinion.

Cheers

Quote - > Quote - And for texturing:  shorter, finer eyelashes and heavier brows. 

For which gender? 

If it is for males, then you are generalizing.  Being male, I have long eyelashes; so does my 4 year old grandson.  It is a genetic trait.

chuckle  Generalizing....perhaps so!  (I am just the opposite!  My lashes are nearly non-existant, and I have heavy brows... and get the "Excuse me, sir....ooops, miss!" comment constantly at work!)

LOL!

Yes, but you didn't add SSS to the default Alyson2 skin texture without makeup to match the render.  Unless there is no texture to work with.

there is a golden main human ratio for pretty girls .
Luis Royo is the best at soft females.

boys are hard .square face jaw eyes lips nose every thing

girls are soft. circular face jaw eyes lips nose every thing.
round,full,fat  lips ,cheeks. short nose.

ya can see how this is magnified in comic,anime.

girls tips will tell you where eye brows belong.

load V4,M4 or V6,M6 with no textures ,look at the diffrences in there face.

ever wounder how millions of people could all look diffrent ?

There's a lot of very small adjustments can be made to the face.

in real life it's only a few hairs width from boys to girls face.

there's a saying "natures gold is green."

no matter her age ,the younger her face looks ,the prettier she'll be considered.
and the closer her face ratio is to the golden main.

Quote - A beard will do it every time :)

ha ha ha.. beat me too it.

You can check out this athlete Caster Semenya http://www.cnn.com/2012/08/08/health/athletes-gender-testing/