with my in laws there is always the underlying cultural thing that a boy is better than a girl, especially a first born is supposed to be a boy. We had a girl first and when we had a boy last year MIL said to OH "Arent you proud now you have a son" He said "I was proud when I had a daughter thanks mum!"
Now i'm pregnant with a girl and BIL/SIL have just announced their pregnancy and if it's a boy I know it will be seen ,(even if they deny it consciously) as more successful....but hey ho.
Gender can be a sensitive area