Final answer:
The sex of a baby is determined by the sex chromosomes, with the Y chromosome playing a pivotal role. Females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). It is the sperm from the male that determines the sex of the offspring, as it can carry either an X or a Y chromosome.
Step-by-step explanation:
The Gender Determination in Offspring
When considering what determines if a baby will be male or female, it is essential to understand the role of sex chromosomes. Females are typically XX, meaning they have two X chromosomes, while males are XY, having one X and one Y chromosome. If a baby inherits an X chromosome from the father and an X chromosome from the mother, the child will be female. However, if the father's sperm carries the Y chromosome, the baby will be male. This is because the Y chromosome contains the SRY gene, which is critical for initiating the development of male characteristics. The process of sex-linked inheritance indicates that it is actually the male's gametes that determine the sex of the offspring, as the mother can only pass on an X chromosome. Therefore, every conception has a 50:50 chance of resulting in a male or female child.
The nature of both male and female gametes plays a crucial role in this process. Male gametes can carry either an X or Y chromosome, whereas female gametes only carry an X chromosome. The fertilization event, wherein a spermatozoon carrying either an X or Y chromosome fuses with an ova, is what ultimately results in the sex of the offspring. The X chromosome is substantially larger and carries more genes, most unrelated to sex, whereas the Y chromosome's primary significance is in determining male gender through the presence of the SRY gene.