However, making merit on birthday did not occur in the past 300 years. Ancient Thais believed that birthdate was one of the top secret that telling someone else was forbidden because it was dealing with black magic. If bad people knew your birthdate, they could easily put the on you. Therefore, there was no birthday celebrating in your past.
The trend has changed to what totally different between the old fashion and the new one. Birthdate is no longer secret anymore. On the contrary, people nowadays love to telling other their birthdates, without fearing of any black magic.