An intriguing entry into the Naked Science documentary series, In the Womb: Identical Twins examines the elusive mysteries of the human species from its earliest stages. Utilizing highly advanced 4-D ultrasound imagery and painstakingly rendered computerized graphics, the film illustrates the processes that determine both the similarities and the differences between identical twins while they develop in the womb.
Born from the same fertilized egg, identical twins often share common physical attributes, social interests and personality traits. As shown in one of the many personal stories featured in the film, even those twins who are separated at birth can engage in strikingly similar life journeys. These common bonds are proof positive that the genetic make-up of the human species goes a long way in determining everything from the color of our skin to our sexual orientation.
However, it’s the differences between these identical twins that pose the greatest potential for new discovery. In an extreme example of nature versus nurture, we’re shown one set of twins who were born with vastly different birth weights. Does the explanation for this phenomenon transcend mere genetics, and more directly reflect their individual experiences in the womb? Embryologists pinpoint the disadvantages of existing within a shared placenta, and how it can lead to a lack of nourishment and severe life-long health challenges for one of the twins.
Other segments of the film illuminate the precarious nature of human embryonic development. A single deviation in the process might seem benign at the moment of occurrence, but can ultimately lead to crippling deformity. In one case, a newborn literally absorbs the limbs of her twin. In another, a twin is born with both male and female genitalia.
Throughout the course of its fascinating narrative, In the Womb: Identical Twins tackles a series of challenging scientific questions. Is homosexuality strictly the result of genetics, or do other factors play a more central role? To what extent is the entirety of our lives determined by our first nine months of development?
The film’s revelations deepen our understanding of the human species, and show us that there is much we have yet to learn.