I'll stick my head up over the parapet and admit I wanted a particular sex when I had no3. I had two boys already and once I was pg I more and more wanted another boy. The gender hadn't crossed my mind when we decided to go for no3 but the feelings developed as my bump did, although they certainly didn't dominate the pg.
I was disappointed when dd was born and had a pretty torrid night afterwards, in tears partly because I suspected she had Downs and partly because I thought I'd never be able to cope with a girl, take care of her or ever know or understand what she would want. I was scared of her.
Next day, I was told by an ill-informed dr that I wouldn't be allowed to breast feed due to my underactive thyroid. The Mummy Tiger hormones roared into life and I went ballistic. No one was going to tell me how to look after my daughter and all hell broke out on the ward. I felt an overwhelming tidalwave-sized surge of love for my tiny baby and suddenly she was the most perfect baby anyone could ever have wanted.
My feelings may have been because my mum always preferred boys and she and I don't have a close relationship, and because I felt I 'knew' boys. I was too embarrassed/ashamed to share my concern with anyone except dh. I'm usually fairly level headed and really, it was an out-of-the-ordinary experience for me to be unable to control that desire. I certainly didn't choose to feel that way and had tried to be positive in pg, looking at girly pink clothes (I don't like blue, lol!) and seeing other people happy with their girls.
So I do have a certain sympathy for Nutcracker's friend, although I think if I'd been desperate for a third boy beforehand I'd probably have forgone another baby rather than risk disppointment. Anyway, this is a long ramble saying notalot, just IME but I hope once the baby is here that your friend loves it as she loves her dd's, Nutcracker.