Kate Gosselin and Jon Gosselin sent love to their twin daughters, Cara and Mady, on the pair's 18th birthday.

Kate, 43, and Jon, 41, marked the milestone Monday by dedicating sweet posts to Cara and Mady on Instagram.

Kate shared a slideshow on Instagram ahead of the twins' birthday celebration. The photos show a birthday cake with sprinkles, personalized M&Ms and gold and black decorations.

"HAPPY 18th Birthday, Cara and Madelyn! There are no words to describe how proud I am of you both," Kate wrote.

"Despite the many turbulent times you've had to deal with so far in life, you have emerged as wise, level headed, reasonable, forgiving, loving, kind and absolutely brilliant ADULTS!"

"You will thrive in life, I am certain, and I will still be with you every step of the way going forward, continuing to guide you and love you," she added.

"I love you both so very very much and I wish peace, happiness and the great successes I know are coming your way!"

Kate followed up by posting a picture of Cara and Mady at their birthday party.

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"My adult daughters: @mady.gosselin and @cara.gosselin," she wrote. "#SoProud What a fun memory filled day we had together today!!"

Jon wished Cara and Mady a happy birthday in a post on his own account.

"Happy 18th Birthday!!! To my twin girls, Mady & Cara!!! Love, Dad," he wrote.

Kate and Jon split in 2009 after 10 years of marriage.

The pair are also parents to 14-year-old sextuplets Aaden, Alexis, Collin, Hannah, Joel and Leah, who started eighth grade in August.