I hate them. I hate being the center of attention and I hate being the host and having to make it worth the time for my quests. I stopped celebrating them as much as possible.
Most of the time I even forget it and only my mother reminds me that I should at least pretend to celebrate for the old folks in the family with some coffee and cake.
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It's not your conception day, it's your "you are on this rock on your own" day. For most the exact date would also be kinda hard to nail down ..
There are calenders though that tried that. I think Japan had an age system in the past the used to account for pregnancy.
Edit: Nvm i mixed that up with East asian age reckoning. https://en.wikipedia.org/wiki/East_Asian_age_reckoning