Out shopping with my friends daughter in the pushchair. No relation to me at all. She has blonde hair, brown eyes and I have brown hair and blue eyes.....we really look nothing alike. But I think some people must just assume if you are out with a child, then it must be yours. A lady came up to us and was cooing over the baby and then said 'you look just like your Mummy don't you?!' (referring to me) Really???? Is this just something people say just to make conversation or what?!
(My 4 year old daughter must have picked up on people saying this a lot as well, because we were looking at photos, and there was one of her as a baby with our dog next to her, and she commented 'ahh, don't we look a like'!!!)
Get it all the time with the three unrelated 2 year olds I mind. However, one family of older kids i mind actually do have my colouring and along with my daughter are like little steps, so more likely to all be mine. Wee man from down the road thinks I have 10 kids. I corrected him a few times, but don't bother any more.
I have been told on numerous occasions 'It's a shame your DD looks like your twat of an ex, poor child.' I always think what an awful thing to say about my DD. Even if she does look like him, which imo she doesn't, she is beautiful to me, and I will never look at her and feel shame. Some people are very thoughtless!
I think people just say it to be nice, but personally I steer clear of this subject because it can open a can of worms... the person could be adopted or resemble a parent who was absent/passed away etc. That's really insensitive of the person who said that to you portaloo. When I was a kid people always commented how much I looked like my dad and nothing like my mum - this was quite perplexing for me since she was a single mum and I had very little contact with the other side of the family. Even people who hadn't seen my dad and only mum would say how unlike her I was which was upsetting to me - this might seem a little precious on my part but trust me, this can be a sensitive subject. Having said all that, when dropping mine at school I've often had people assume that a friend of theirs I've brought to school with them is also mine, even if that child is clearly of a different racial background, size, age too close to mine or whatever. So yeah, often just small talk, but something I would avoid.
My cousin was looking after my then 12-week-old DD2 and a man congratulated her on her baby then, as she opened her mouth to explain that she wasn't hers, he followed it up with, "you both look very alike... I think it's the cheeks, yes, you have the same cheeks". His wife hung her head in shame and explained to him that it would be best if he stopped now and that cheeks aren't something to comment upon especiallywhenthey'reaschubbyasDD2'swere. My cousin then told him that DD2 wasn't hers... he looked suitably embarrassed.
Our old au pair used to get this when out with DS (they both have curly hair). She said that she used to get all the time with one of her previous charges, as they both have green eyes. I think people just say it to shoot the breeze.
Mind you, she once had someone ask if she was sure DS was a boy - I think some people just engage mouth before brain when they speak.