Chapter 6: When twins unite: hermaphrodites and other stories

When twins merge you get a real two in one personality. It can be very hard to know who you are in this situation - male, or female for example.

Hermaphrodite: If you merged with your DZ twin and they were the same sex as you, then in the absence of any skin or eye colour anomalies, there would be little proof, unless you happened to take a DNA test.  However, if you merged with your DZ twin and they were the opposite sex to you, chimerism may be more easily identified because you would have both male and female DNA in your body. 

This is because the formation of each chromosome in pair number 23 varies according to whether the individual is male or female.  Once the chromosomes are visible under a microscope the different shapes can be clearly seen.  The male chromosome pairs look like the letters “XY” and the female chromosome pairs look like the letters “XX.”  Chimeras that have both male and female DNA are called “XX/XY.” 

Another word for people with mixed-sex DNA is “hermaphrodite.” They are genetically both male and female. If you are a hermaphrodite, you may have XX/XY chromosomes, but that doesn’t say you will also have physical characteristics of the opposite sex. Hermaphrodites can be grouped on a spectrum, depending on the degree to which the opposite sex DNA is expressed physically.  

At the “male” end of the spectrum we have hermaphrodites, who are normal, fertile males and have all their sexual equipment present and intact. At the opposite “female” end, we have hermaphrodites who look like normal, fertile females, also with their sexual organs present. 

In the middle of this spectrum there are people with the sexual characteristics of the opposite sex.  They are described as “inter-sex” if their bodies express both sexes, such as having both sets of genitalia.  They are “trans-sexual” if they begin life as one sex but have an overwhelming desire to change to the opposite sex.  In the medical literature there is so much emphasis on people with sexual ambiguity, that the “normal” male/female chimeras remain unnoticed, simply because they look and act normal.

And there is still more to learn about prental life - tomorrow we will look at how you related to the objects in the womb that were there all around you.