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Lesson: Chapter 20 — Heredity

20.5. Sex determination 6 of 6

Question 6

A couple already has three daughters. What is the chance that their fourth child is a son?

The right answer is the one marked above.

One in two, exactly as for the first child. Each conception is an independent event. The three daughters already born have no effect on the next one.

This is the same point as the four pea seeds. Believing otherwise is common, and in the case of sex determination it has caused real harm.

Answer the question to continue.