My sister carried heavily with both her pregnancies (put on approx 20kgs each time) and both were boys.

On the flipside, a close friend had very neat, basketball type bumps with both her pregnancies and you could hardly tell she was pregnant from behind and both were girls.

I don't believe in any of the myths now and I'm quick to tell people that when they tell me 'oh you're definitely having a.....' based on my size, shape, skin condition, cravings, etc. They just make me laugh!