Does the father or the mother cause the gender of the baby? I had a dispute on this today?

My friend and his wife were in for coffee today and talking about how they were trying for a baby. They said it was likely going to be a girl because girls ran in his wives family. I have already heard the genes that determine the gender of a baby are from the father and not the mother. No genes from the mother... show more My friend and his wife were in for coffee today and talking about how they were trying for a baby. They said it was likely going to be a girl because girls ran in his wives family. I have already heard the genes that determine the gender of a baby are from the father and not the mother. No genes from the mother have any role in determining or causing gender, its fully XY chromosomes from the man.

What way is it? Which way is the baby determined?
Update: Patryk, there is no need to be smart. I am 90 years old just to let you know and I was pretty sure it was the man just wanted to clarify it.
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