The ageless beauty's sibling, Jeffery, died in 1976 at the age of three and Crawford admits she does all she can to raise awareness and cash in memory of him.
Appearing on Access Hollywood Live on Thursday (08Mar12), she said, ""Because of that experience for me and my family, my mother, part of her grieving process, was to start a dance marathon in our town. So, even at a young age, I kinda saw, 'Wow, you can make a difference.'
""As my career took off and I was able to lend my name to raise awareness or to help raise money... that's my passion - pediatric oncology, specifically.""
And, as a mum, Crawford admits she can't imagine what it was like for her own mother to lose a child.
She told hosts Billy Bush and Kit Hoover, ""I remember maybe three days after my first child was born calling my mother, going, 'OK, how did you do it? How did you survive that?'
""She goes, 'I had three other kids looking at me like, 'OK, what's for breakfast and how are we gonna move on?''""
And Crawford often sees her late brother in the children she visits in hospital: ""A lot of them are bald and I remember when my brother was bald and how self-conscious he was; he would always wear this little red hat... And a lot of them are on (drug) Prednisone, which makes them tend to be really hungry, like my brother... so he got a little puffy... and when I see other kids like that, that really takes me back to how I remember him at the end.""