What makes us a woman? The simple answer would be — our ‘female’ DNA. Unfortunately, like many other things in life, nothing is simple. Least of all what we make of our DNA.
Back to basics
Firstly, let us ponder on that word, ‘female’. This word could be used for both ‘gender’ and ‘sex’. The female gender refers to the feminine characteristics which are mostly influenced by society. The female sex however is biologically determined. However, the terms sex and gender, for both male and female are usually used interchangeably.
Human beings are made of cells. All cells except for reproductive cells, have 46 chromosomes. Those 46 chromosomes are arranged in pairs hence we have 23 pairs in each cell. Out of the 23 pairs, 22 are called autosomes and the last pair is called sex chromosomes.
Life with one less X
The X and Y chromosomes are sex chromosomes. They determine a person’s sex. We were taught in our secondary school that men are XY (written as 46XY), women are XX (written as 46XX). Research suggests that some female babies can be born with a single X (45X) instead of two. They are known as Turner Syndrome. A baby who has Turner syndrome usually grow up with a short stature, with a heart shaped face, has webbing of her neck, possibly has a heart lesion and elbow deformities as well as a poorly developed gonadal/reproductive tract.
A fetus can also have only one Y, without an X chromosome (45Y). However, this genetic combination is not compatible with life. Clearly the X chromosome is needed for survival.
Females with a Y
Some fetuses are born with more than one sex chromosomes. These are called sex polysomies, for example 47XXX. These babies will grow up to be tall females with normal mental development (unfortunately the extra X does not make one a Superwoman!).
There are also fetuses born with 47XXY. Even though the baby has a pair of X chromosome, the baby external appearance is of a male baby. This is because, the presence of the Y chromosome act as the main inducer for the male appearance (also known as the male ‘phenotype’). Another example will be an individual with 48XXXY, who will also have a male phenotype due to the presence of a Y chromosome.