The gender of the child is randomly set at the time of the marriage ceremony. There isn't a way to control what gender your child is, much like a pregnancy in real life.
I saw on the game of my brother that he had a girl in the third year and then I looked at mine and I had a girl in the fourth year.I thought that maybe females born in uneven years,and the males in the even years and then I searched on the website to have a confirmation.