The pagans believed that the day you were born had some spiritual power and that it was to be celebrated.  Roman Emperors were thought to be gods and therefore demanded worship on their birthdays.  Cakes were originally baked to the moon goddess and blowing out candes and making a wish were to all upon your muse to grant you that wish, almost like a genie.

Additionally, Ecc 7 says the day of one’s death is better than his birth as you really had nothing to do with coming into this world.  The celebration of Yeshua’s birthday is from pagan origins, celebrating the supposed birthday of the sun god  Mithras.  So, birthdays do not line up with Scripture.  Yet, they are fun and a day to celebrate being special and is there anything wrong with that?  Do we forget them all together or should we just modify how we celebrate them?