The 'survey' is clearly tosh but fun to muse upon!
I've one of each and love having both a boy & a girl. However I sometimes mourn the fact that they won't have a same sex sibling and the closeness that that can bring (I have an elder brother and still to this day wish he'd been a sister instead! - a boy/girl combo definitely didn't make for a happy family in our house! - I hope my two fair better in their sibling relationship & thus make for a harmonious household).
I'd say 3 children would be great but my husband has won the argument so, unless I can persuade the milkman, we're sticking with 2.
All hell will break loose when they're teenagers anyway, regardless of gender mix or number of children happy family life will temporarily be suspended!