Who's that?

Is it weird that every time my cousin-in-law posts pictures of her two kids, I totally don't recognize one of them? Every time I wonder, who the hell is that?  It's because my niece looks like a nephew. I have no idea why it seems that way to me...but that kid just does not look like a girl. I haven't met her yet (and maybe that's why). God help me if I ever say this in front of someone in my family, especially her dad. He'd probably feed me to lions.