Half of the children are boys, and the other half are girls because the father can contribute either an X or a Y chromosome. The combination of the X received from the mother and either the X or Y from the father determines the sex of the child.
Why do half of the children, according to Figure, end up being boys and the other half girls?
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Half of the children end up being boys and the other half girls, according to the figure, due to the equal probability of inheriting an X or Y chromosome from the father during fertilization. In human reproduction, the mother always contributes an X chromosome, and the father contributes either an X or a Y chromosome. Since the father has one X and one Y chromosome (XY), there is a 50% chance that the offspring will inherit an X chromosome, resulting in a girl (XX), and a 50% chance they will inherit a Y chromosome, resulting in a boy (XY).
This equal likelihood of inheriting an X or Y chromosome ensures a balanced distribution of male and female offspring, making the probability of having boys and girls approximately equal in the population. The figure reflects the random nature of genetic inheritance, contributing to the diversity in the sex composition of offspring.