Randomly gift your loved ones at different times of the year so that you do not feel obligated to promote the birthday culture.
Randomly tell them how much they mean to you and how proud you are of them. They might need to hear it the most on a day when it is not their ‘birthday’, not to mention how sincere it would feel if you did not wait for that one day of the year to sing with the crowd.
I once came across a woman on Instagram who would often get a cake for her son to celebrate his achievements (like doing well in class) so it would not be that he gets no cake because he does not celebrate his birthday.
Certain things are only as significant as we make them seem.