A theory that seemed to work (this time) is when Mrs Busybody comes on odd numbered visits you get a boy and on even numbered visits you get a girl, this is working on the basis of 3 visits per day (even if you don't see the visit).
I'm sorry but I don't agree with this because I always say yes when the matchmaker comes the first time and sometimes I get a boy and sometimes I get a girl (but most of the time a boy).