Ellen Pompeo says her children's friends don't think she's their mother - because of the colour of their skin.

Ellen Pompeo

Ellen Pompeo

The 49-year-old actress has three children - daughters Stella, nine, and Sienna, four, as well as son Eli, who turns two this month - with her husband Chris Ivery, and has said she was left heartbroken when her eldest daughter's friends were surprised to discover she was her mother, because the actress is white.

Ellen said: "My challenge with raising brown children is how much do you say to them and how much do you not say to them?

"A couple of weeks ago I had some friends over [to] the house, little girls of color, and the little girl came in and I introduced myself. I said, 'I'm Stella's mom.' ... She went right to Stella and said, 'That's your mom?' She points to the nanny who's a black girl [and says,] 'I thought that was your mom.' The little baby looked like she was scared of me. That just breaks my heart. Maybe scared is a strong word ... but, again, non-trusting possibly.

"That experience of being in my house and meeting me was good for her to see that all white people aren't what you think. As moms and dads, we have the responsibility to expose our children to all different types of people. To show them the differences in the world."

The 'Grey's Anatomy' star says she knows her daughters will be treated differently because of the colour of their skin, but says her son - who, along with second daughter Sienna, was born via surrogacy - "looks completely white".

Speaking during an appearance on Jada Pinkett Smith's Facebook Watch show 'Red Table Talk', she added: "My son looks completely white. You couldn't even tell that he has any brown in him at all. There is no escaping when your skin is dark. That's why my children are brown or whatever it is. Because the world will see them that way and they will be discriminated against and they will be judged and they will be spoken to and they will be treated like they are brown because their skin is brown."