Ultrasound

I did another ultrasound in 3d and the baby again did not want to open the legs so the tech said it could be a girl cause it's shy 80% and that's my 3rd ultrasound and stil legs are closed . Does that mean it is a girl? Boys don't close the legs? Or does something have to dangle when the legs are closed to know? The baby kept smiling through out the ultrasound like to say I will not show u guys what i am lol