Cindy Crawford Opens Up to Oprah About Her Brother Dying of Cancer at 3 Years Old

Plus, Cindy Crawford's lookalike daughter Kaia lands her first modeling contract.

Cindy Crawford is opening up about a family tragedy in her past.

In a preview for her appearance on Oprah's Master Class on OWN, the 49-year-old supermodel talks about her younger brother, Jeff, who died of leukemia when he was just 3 years old. Crawford was 8 years old when Jeff was first diagnosed. He was only 2 years old at the time.

"I think when my parents first told us our brother was sick, we didn't really understand what it meant," Crawford recalls, referring to her and her two older sisters, Chris and Danielle. "They didn't use the word 'cancer.'"

WATCH: Rande Gerber Reveals the Secret to His 17-Year Marriage to Cindy Crawford

The Crawford family then went to the hospital -- a two-hour drive -- for radiation treatment almost every day. After deciding to put Jeff in an experimental program -- and Jeff continually going into remission only for the cancer to return -- he eventually passed.

Clearly, the memories are still heartbreaking to this day.

"Right before he died he had told all his doctors, 'I'm not coming back.' ... There's some sense of completeness and peace that comes with knowing that he knew that, and he kind of decided he was done fighting," Crawford remembers. "I don't think that at age 10 that I knew that it was terminal, and I had not had any close experience with death and did not understand death. My brother did know. At one point for sure I know, because my mother said she found him sitting in his room. He was sitting at his little table, and she said, ‘What are you doing?’ And he said, ‘I’m praying.’ And she said, ‘What are you praying about?’ He said, ‘So that when I die, you’ll be OK.’ As a mom now, I can’t imagine hearing your child say that."

Crawford is of course now a mother herself to her two kids with husband Rande Gerber, 15-year-old Presley Walker and 13-year-old Kaia. Kaia continuously makes headlines for her amazing lookalike genes, and just landed her first modeling contract with IMG models.

Check her out expertly rocking a suit in this stunning new photo by photographer Steven Meisel for Vogue Italia.

"Guess I better watch my back..." Crawford joked, re-posting the sophisticated shot.

WATCH: Kaia Gerber Steals Cindy Crawford's Dress!

ET recently caught up with Rande, when he joked about buying "a shotgun" in response to his gorgeous daughter's growing fame. Watch below!