Alicia Keys celebrates 'unstoppable' stepson, Kassem Jr.

Alicia Keys is a proud stepmom!

As Kassem Jr, turns 18 years old, the 43-year-old artist took to her official Instagram account to pen a heartfelt birthday wish for the young man.

Underneath a carousel of lovely images that was comprised of snaps featuring him and Keys, as well as some family pictures, she wished her stepson, who goes by the name, KJ, with a note.

"My amazing young king @yayachronicles !! You are totally unstoppable!! I’m so excited about every moment this year is going to bring!! This is just the beginning of things you can’t even imagine!" the Girl on Fire hitmaker wrote.

It can also be seen in the post that KJ is wearing a NYU sweatshirt, over which Keys mentioned in the caption, "Keep working hard and bringing that light and gratitude, everywhere you go!!!! The blessings of tomorrow will be greater than we can ever imagine today!!! I love you Kassy!! Always your Umi!!! Congratulations on NYU babyyyyyyyy!!!!!!!! letssss gooooo!!!!!!!!"

For the unversed, Alicia Keys’ husband, Swizz Beatz, shares KJ with ex-wife, Mashonda Tifrere. He is also a father to son Prince Nasir, whom he shares with former partner Nicole Levy and to daughter Nicole Dean, whom he had with singer Jahna Sebastian.

Meanwhile, Keys and Beatz themselves share two children together, that is 14-year-old Egypt Daoud and nine-year-old, Genesis Ali.