Nephew is really attached and being a mommas boy, his mom found out today she's a having a boy. My…

Nephew is really attached and being a mommas boy, his mom found out today she's a having a boy. My nephew has been the complete opposite with me. He screams at me , gets mad and starts throwing temper tantrums with me. Everyone in my family is saying that I'm having a girl. I honestly feel the same. Has anyone experienced this?