In having children, is there a genetic factor that causes some families to favor one sex over the other? That is, does having boys or girls “run in the family”? This was the question of interest in Chance (Fall 2001). Using data collected on children’s sex for over 4,000 American families that had at least two children, the researchers compiled the accompanying table. Make an inference about whether having boys or girls “runs in the family.”

Sex Composition of

First Two Children Frequency

Boy–Boy ..........1,085

Boy–Girl ..........1,086

Girl–Boy ..........1,111

Girl–Girl .......... 926

Total ..........4,208