Are celebrating birthdays allowed? Does any celebration that we celebrate today that has origins in pagan traditions become disallowed as a result?
We don't have enough evidence to say celebrating birthdays is not allowed as far as it does not include sinful act and does not support un Islamic way of life.
Un-Islamic acts are not allowed after our leading scholars ( Maraaji' of Taqleed) confirm that it is definitely un-Islamic according to authentic evidence from Quran and Sunnah and not only according to cultural reasons.
Wassalam.