So im 27 weeks now and have a 4D appointment scheduled for January 9th. I had a very detailed scan done at 18 weeks checking for a Desease my brother had... My ultrasound tech asked if i wanted to know the gender and i said yes. She told me its a boy. I asked how sure she was.. she said she was 90 percent sure. But now im worried that when i go to my 4D ultrasound they are going to tell me its a girl... What are the chances this will happen??