Question

A certain couple got only four daughters in a row and no son. Does it mean that the husband does not produce Y-bearing sperms? Explain.

Answer 1

No, it does not mean that the husband is incapable of producing Y-bearing sperm. During conception, half of the ejaculated sperm carry X chromosomes, and the other half carry Y chromosomes. In these cases, only X-bearing sperm successfully fertilise the wife’s eggs each time. Random chance accounts for this outcome, as each pregnancy has a 50% chance of producing a male or female child.