4.6.1. Sex Determination in Humans

It has already been mentioned that the sex determining mechanism in case of humans is XY type. Out of 23 pairs of chromosomes present, 22 pairs are exactly same in both males and females; these are the autosomes. A pair of X-chromosomes are present in the female, whereas the presence of an X and Y chromosome are determinant of the male characteristic.

In humans, sex determination follows the XY chromosome system. Each human has 23 pairs of chromosomes, which include 22 pairs of autosomes that are the same in both sexes. The 23rd pair is the sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). This difference in sex chromosomes is what determines a person's sex.

Think of chromosomal pairs like a team: in a soccer match, a female team has two players in the same color uniform (XX), while a male team has one player in each color (XY). The different combinations determine how the teams (genders) are formed.

During spermatogenesis among males, two types of gametes are produced. 50 per cent of the total sperm produced carry the X-chromosome and the rest 50 per cent has Y-chromosome besides the autosomes. Females, however, produce only one type of ovum with an X-chromosome.

Males produce sperm cells that can carry either an X or a Y chromosome; this results in a 50% chance for each type. In contrast, females produce eggs that all carry an X chromosome. When a sperm fertilizes an ovum, the genetic combination determines the sex of the offspring. If an X-carrying sperm fertilizes the ovum, the result is female (XX). If a Y-carrying sperm does so, the result is male (XY).

Consider a lottery draw. In the male's lottery, you have two chances: one ticket has an 'X' and another has 'Y'. The female lottery ticket only has 'X'. When combined, you can get either a ticket with two 'X's or an 'X' and 'Y', determining the sex of the offspring much like how a lottery draw determines the winner.

There is an equal probability of fertilisation of the ovum with the sperm carrying either X or Y chromosome. In case the ovum fertilises with a sperm carrying X-chromosome the zygote develops into a female (XX) and the fertilisation of ovum with Y-chromosome carrying sperm results into a male offspring.

Since males produce equal numbers of sperm containing X and Y chromosomes, there is a 50% chance for either gender when a sperm fertilizes an egg. If the sperm carrying the X chromosome fertilizes the egg, the result is a female (XX). If the sperm carrying the Y chromosome fertilizes the egg, a male (XY) is produced.

Imagine tossing a coin where heads represent a girl and tails represent a boy. Every time you toss, there's a 50% chance of landing on heads or tails. Similarly, the equal likelihood of X or Y chromosome from the sperm creates this 50-50 gender balance.

It is unfortunate that in our society women are blamed for giving birth to female children and have been ostracised and ill-treated because of this false notion.

Despite the biological evidence that the sperm determines the sex of the child, societal beliefs often place blame on women for the gender of their children. This misconception can lead to severe consequences for women and continues to perpetuate gender discrimination.

This situation can be likened to blaming a weather forecaster for rain. The forecaster provides information based on the conditions (sperm genetics), but they don't control the weather itself (the outcome of the child's sex). Blaming women for the birth of daughters is equally misguided.

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