One associasted with the JWs has claimed that Russell got the birthday ideas from the bible and it's disclosure of 2 birthday which had tragic consequences, such as The daughter-in-law of Pilate wanting the head of John the Baptist on a silver platter for her birthday. Evidently the one who presented this thought that Russell taught that one should not celebrate birthdays.
The reality is that Brother Russell never objected to birthdays; the Daily Manna in his day carried spaces for recording the birthdays of others.