Many of the Teen Mom stars have to contend with difficult relationships with their baby daddies, but Farrah Abraham must deal with his absence.
Farrah marked Derek Underwood's birthday today. Derek died in a car accident December 28, 2008 — just two months before baby Sophia was born.
"Happy Birthday to daddy Derek. We love & miss you, may you RIP. Hugs & kisses from Sophia & Farrah <3," she tweeted today.
Farrah and Derek had a rocky relationship before his death, but she has always mourned that he wasn't in his daughter's life.
"It's hard to deal with the fact that Sophia never got to meet her dad," she told Us Weekly.
"He would have been loving and supportive and taken care of both of us. When Sophia was born, her face looked just like his, and so did her toes!"
RIP Derek. Watch a clip of Farrah and Sophia visiting his grave on Teen Mom.