In France, I’d say these are special birthdays :
1 – because it’s the first
18 – because it’s when you’re officially an adult (it’s when you can legally drink alcohol and drive a car -more important)
20 – because you’re now the youngest “0”-aged adult you’ll ever be. There’s an old song from 1934 that goes:
“On n’a pas tous les jours vingt ans
Ça nous arrive une fois seulement
C’est le jour le plus beau d’ la vie…”
“We aren’t 20 years old every day
It only happens once to us
It’s the most beautiful day of life…”
All the “0” ages… 50 being the most important, maybe because it’s half of 100 and it’s considered you enter “l’âge mûr” = maturity.
I’d say 65 is important since it is the normal retirement age. By the way, the retirement age of 65 is totally arbitrary.
Checking in from Japan where the 20th birthday is a big deal. 20 is the official beginning of adulthood and its’ attendant benefits…drinking, smoking, and voting.
The second Monday in January is a National holiday called Coming of Age Day (Seijin no Hi). On that day, municipal governments around Japan hold ceremonies for residents turning 20 that year. Men wear suits and women wear a particularly formal type of kimono. In recent years the media has had a field day reporting on disturbances during and after these ceremonies caused by drunken, beligerent coming-of-agers, but for the most part, they are respectful affairs.
I found out why 60 is an important birthday in the Chinese culture. It’s because it represents a full cycle of the Chinese calendar, which takes 60 years to complete.
Many people in the U.S. have special parties for their daughter’s 16th birthday, called Sweet Sixteen.