It is interesting to see what people do believe in. Some, like not swallowing the seed, had a basis in trying to prevent digestive problems and some seeds have cyanide in them. But that would be too hard for kids to understand.
The cutting the nails was probably a coincidence and became folklore.
Visiting you from MAP
Thank you so much @mariannewest for reading my post. Filipinos have a lot of superstitious beliefs and most people, especially the elders, believed in it.