hot for girl babies (it kills the boy sperm) and cold for boys. So tight pants/tousers for a girl apparently. Apparently loads of girls born in 60's and they couldn't work out why and then worked out it may be due to the fashion for tight trousers.
I'm preg with DC3 and was trying for a girl this time so been reading up loads on what you need to do. There's more to it than sperm though - timing very important and also diet factor too. See Shettles or Hazel chesterman smith.