I had a friend in high school who believed that all dogs were male and all cats were female and when they mated, half of the litter were puppies & the other half kittens.
One of the most bizarre things I’ve ever heard, though, came from my aunt after my nephew was born. She was actually my great aunt, my grandmother’s sister, so this must have been some kind of old wives’ tale - when you clip an infant’s nails for the first time, the mother has to eat the clippings or…something will happen. This was about 20 years ago and I can’t remember the penalty now. I do remember the entire room staying uncomfortably quiet for while after she dropped that pearl of wisdom.