The skull theory uses the ultrasound picture of your baby to determine the gender. The idea is that the shape of the baby's skull can predict whether it will be a boy or girl. For example, the top of the head for a girl is rounder and tapers at the top whilst if it is a boy the top of the head is likely to be more blocky and big.


There is definitely a a difference between male and females skull shapes, however these differences are only seen in ADULTS or MONKEY'S. We know baby's move constantly in the womb and therefore can show their skull shape to look differently. One move and they look like they have boy skull shape the next they appear as if they have a girl skull shape.

Example below of the same baby showing different skull shapes.


Most important skull differences between men and women are indicated by the letter value on the figure to the left and described below: 

To determine gender, use the following criteria:

  • (A)The male cranial mass is blockier and more massive compared to the females, which is rounder and tapers at the top.

  • (B)Temporal Ridge – this runs along the outer side of the upper skull creating the square shape of the upper head. More prominent in men than women.

  • (C) A woman’s supraorbital margin (the ridge above the eyes) is sharper, while the males are round and dull. 

  • (D) The Zygomatic bone (the cheekbone that lies under the lower eye ridge) is more pronounced on the male skull. 

  • (E) The Mandible (lower jaw) bone of a woman is rounded, while the male’s is squared. 

  • (F) Frontal bone forehead structure terminates at the brow. The male forehead is lower and more sloping. 

  • (G) Men have a deeper cranial mass. 

  • (H)The superciliary arch is large and pronounced in the man. 

  • (I) A males gonion (the most posterior inferior point on the angle of mandible) is more flared out and sharply angled. 

  • (J)The teeth of men tend to be larger. 

The information provided to you is backed by many years of knowledge on the nub theory. We are not medical professionals nor do we provide medical advice.

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