Time for some sisterly affection and SM love!  Girls' Generation's Jessica wished her younger sister f(x)'s Krystal (or Soo Jung) a happy birthday.

On the 24th, Jessica updated her Weibo with a very sweet message, "Krystal's 20th birthday!  Thank you, Mom. Krystal is the most precious and lovable person on earth. You were born well, Soo Jung." 

SEE ALSO: 'Our Blues' actress Jung Eun Hye to tie the knot in May

She also put up a 4-set picture of the two sisters doing cute poses and hand signs together, showing off their striking similarity and beauty.  They did hand signs to show Krystal's new age, a proud twenty that led her out of her teen years--well, in Korea anyway. 

Likewise, fellow f(x) member Luna also posted pictures of herself with Krystal.  She wrote on her me2day, "f(x) maknae, Krystal.  My pretty~ happy birthday!  I will pray for only happy things to happen to you today."

Happy birthday, Krystal!