calamityjam - I had a similar situation with DS (11) when he was a newborn. He was born in hospital but home within 6 hours, so we had a team of midwives visiting us "in the community" (as they called it). One of them looked at me, a Caucasian woman, and my ex-P, a Caucasian man, and at DD, who is paler than pale (she never tans... and believe me, she's tried!), and then at my 3 day old DS, also of Caucasian origins and said...
"Is his natural father Indian? Because he's very dark..."
It caused a huge row between ex-P and myself - and I'll be honest, if DS wasn't facially the image of his paternal aunt, there may well have been accusations of him not being ex-P's child and paternity tests when we eventually cut all ties to our relationship. My ex's mother had already heavily suggested during my pregnancy that her darling son couldn't possibly be the father of my DC because we didn't live together (no, because he decided to go travelling in Thailand and Vietnam when DD was a newborn baby and didn't come back until she was almost 3 years old... and I learned how to cope by myself!).
Turns out that DS had severe jaundice, which had been missed by the team in the hospital. Another of the visiting midwives (older and with more experience) picked up on it 3 days later. He should never have been allowed home at 6 hours old, apparently.
Was I offended by her comment...? Other than the fact that it caused a huge row between myself and his father? No. Because I knew DS was ex's child. Without a doubt. Can I trace the demise of our relationship, once and for all, back to that midwife's comment? Probably, if I cared enough to. It sowed the final seed of doubt in both of our minds, I suspect, that neither of us actually wanted to be with the other - but it took another few years to get that far...
DS being okay was all that I cared about, and he was, so it worked out. Even if I will never forget what was said...