Assuming no realism-based limits on the number of boys each couple can have, I'd have said greater odds of more boys than girls...there can be anywhere from 0 to infinity boys, but only as many girls as there are couples. The number of ways for there to be more boys than girls is therefore greater than the number of ways for there to be more girls than boys. But that ignores the decreasing likelihood of increasing successive male births. Taking that into account, expected balance is almost exactly equal.