Girl or boy?

Hey mommas so I’m 13 weeks pregnant and I had a question on gender so I’m Hispanic and we have a strong believe (well me Not so sure) that if it’s going to be a girl your whole body gains weight like thighs butt and stomach and if it’s a boy only your tummy gets big well I’m a thin person so even if I get preg I don’t think I will gain weight. Do you ladies think this is true??