To help solve an acute national over-population problem, a government issues a radical decree that families must stop having children as soon as they have had one son. After a while, there are some families with only one boy, some with one girl and one boy, some with two girls and one boy, some with three girls and one boy, some with six girls and one boy, etc., and some families only have girls and give up trying for a son.
Would boys tend to outnumber girls in this generation? Or vice versa?
Regardless of the decrees issued by the government, the ratio of boys to girls born is unchanged. Whoever the next mother in the country to give birth is, she always has a 50-50 chance of boy or girl.