Could do with a bit of 'form' here Jackyalex .. i.e. which is the sex most prevelant in the father's side ... their contribution which decides the sex after all ..
Name of your sister's first born, usually the mother who chooses the name, and can see if she has a traditional leaning, modern leaning, etc.
Could be good to know the surname, as certain names would not 'flow'.
Ok .. just digging ..