'21 is over-rated as a milestone. I guess kids in US reach adulthood at 21 and kids in Europe at 18.'

i do not agree with the content 'kids in Europe at 18'

reason:
i met a european girl who has just turned 21 and allowed to enter in the nightclub ..she is the most beautiful girl i have ever seen..(well i do always feel the same when i see every other beautiful girl)
The European girl hesitates to twerk neither was ready to grind unlike all the freaking white chicks and black booties in the club. and at once she was smiling and a little bit shy as well looking at me. i knew the reason but still i asked her why and the reason was a guy and a girl(of course white american) in front of her and sojoketo were kissing right in front of the mass in the night dance club..
so the assumption that girls from Europe at 18 turns to have the adulthood at 18 is not always right.
IMO, American girls are the craziest freaking forward  one who reaches the adulthood at 21, of course after 21 and ever before 21, most of the time even before 18..