I think having a child is a big step in life, and changes people a lot, because once they do they realize that they have responsibilities, a duty to be fulfilled to give that child the best they could give so he can grow up and be a good person, and gamblers of all people start losing their passion and their addiction for gambling because the money they go spending in the casino is best to be saved or given to that child.
Getting responsibility will definitely give you a big change but it doesn't mean that as a gambler you have to change. It only adds you something that you need to sustain as a parent, not all are the same. There are some that changes and there are some that doesn't.