I read somewhere that higher chance of getting boys in colder climates, can't remember why and also dont know if it's proven really true or not scientifically. but my boy was conceived when dear husband and I were holidaying in the highlands in Msia. Heehee...But we didn't plan it intentionally. We just let nature take its course.
What is scientifically true is that male-producing Y-chromosome moves faster but survives only 24h whereas female-producing X-chromosone can survive a couple of days. So technically speaking, it's higher chance to get females unless the 'soldier' is mobilised at perfect timing very close to your ovulation.
Books also say if want girl, the couple needs to take more acidic food. If want boy, more alkaline food. You can try googling for the detailed info. Lots of websites on this topic.
All the best!