When did you become genetically male or female?
A. At the moment of conception
B. During the embryonic stage
C. During the second trimester of development
D. During the third trimester of development
The correct answer and explanation is:
The correct answer is A. At the moment of conception.
At the moment of conception, when a sperm fertilizes an egg, the genetic sex of the individual is determined. This is because the sperm carries either an X or a Y chromosome, and the egg always contributes an X chromosome. If the sperm carries a Y chromosome, the fertilized egg will have an XY chromosome pair, which will develop into a male. If the sperm carries an X chromosome, the resulting pair will be XX, and the individual will develop as female.
The chromosomal sex determination occurs immediately upon fertilization, as the fertilized egg (zygote) contains the full set of chromosomes, including the sex chromosomes. The presence of the Y chromosome in males leads to the activation of specific genes, such as the SRY gene, which triggers the development of male characteristics. Without the Y chromosome, the embryo develops female characteristics.
While the differentiation of the reproductive organs and external genitalia happens later during fetal development, the genetic sex is set right at conception. The development of male or female characteristics becomes visible during the embryonic stage, but the groundwork for these developments is already laid out in the zygote’s chromosomes.
Thus, even before the formation of the internal and external genitalia, the genetic framework of the individual’s sex is established at conception, making this the most accurate answer to the question.