Jehovah's Witnesses don't celebrate any special occasions. I think that it is unusual because there are special times when we take time to lift up others and reflect on their contributions. If there were no holidays and no special occasions, there would be no reason to celebrate. A birthday is an opportunity for others to celebrate you. Some people show affection by 1. spending quality time, 2. gift giving, 3. sharing a talent- service, 4. physical touch, 5. words of affirmation/compliments. So, if your parents show love by 1., 2., and 5., then a birthday is a good time and reason to express and share that love.