Final answer:
Sex of a offspring is determined by the combination of sex chromosomes from both parents, and does not depend on the sex of the previous children. Therefore, there is a 50% chance for the offspring to be a girl.
Step-by-step explanation:
The sex of a baby is determined by the combination of sex chromosomes from both parents. Every baby receives one of two sex chromosomes from their mother – always an X, and one from their father – either an X or a Y chromosome. If a baby inherits an X chromosome from the father, the child will be female (XX), while an inheritance of a Y chromosome will make the child male (XY). It's important to note that each sperm from the father carries either an X or a Y chromosome, and the chance of either being passed on is equal, resulting in a 50 percent chance for either a male (XY) or a female (XX) offspring.
Regardless of the sex of the previous children, each new baby has a 50/50 chance of being either male or female, as the sperm's chromosome is randomly selected every time. Therefore, the final answer to the question 'Sex is determined by the male gamete, which can be carrying either an X or Y chromosome. Thus, there is a ___ chance that it is a girl. Previous offspring have no effect on this outcome.' is a) 50%.
Learn more about Sex Determination