I believe the heart burn one. My first two pregnancy I had heart burn and they came out with head full of hair both of them being boys. I have heart burn with this pregnancy and it's a girl but everyone is joking that she is going to come out bald lol. So we will see..
All myths are a bunch of bologna but they are still fun. Here's some I know of: girls steal the mother's beauty (if you get acne it's a girl). Hairy legs mean a boy. Heartburn means lots of hair for the baby. Sweet cravings are for girls, salty for boys.
Heartburn means baby will have hair, suffered horrendously with my first and she was bald for the 1st year of her life. I'm suffering loads with this one too, so shall see if the myth plays any truth this time, I doubt it tho.
Sour and spicy food cravings for a boy
That girls heartbeat are faster than guys, my girl was at a constant 160 for the first 20 weeks I believe.
More sickness with boys than girls. True for my first. We will see with this next one :)