Ah, the law of probability the best law for making money at roulette!
But, the law of probability does, and doesn't affect the outcome of gender in a child. It depends though. Mathematically it is a sound idea that it is possible due to probable odds.
What really decides if you will have 9 consecutive girls is your D.N.A., as well as your spouses D.N.A., and how fertile the female is. I think that females are more common than males for the most part. But, having 9 girls in a row can happen. Just like having 2 sets of twins, it can happen.