Because event number one is independent of event number two. What that means is the gender of the first child has no effect, no bearing, no influence on the gender of that second child. So we can get a boy and a girl. We can get a boy and a boy or a girl, a girl and a girl or a boy. So we can have four different possibilities as we'll see in just a moment. And these different events, two events are independent of one another in the same way that these two coin flips were independent of one another.