I completely agree @Lockheart I also wonder if it's the actual person in the photo too. IMO, no-one in their right mind would post their OWN PHOTO on mumsnet, (a massively popular message forum that 10s of 1000s of people post on every day, and 100s of 1000s of people read,) asking people how old she looks.
If anyone genuinely does it, it can only be for one reason (IMO.) And that is because they think they look younger than their actual age. Some people think that, and claim that everyone they meet thinks they look MUCH younger than their age.
Funny how no-one ever says people say they look much OLDER. 
In reality, the vast majority of people look their age (within 6 or 7 years in either direction.) No-one looks any younger than that, not when you look at them properly. They may look 12-15 years younger at first glance, if they have 'trendy' clothes and a trendy hairstyle, (ie, are dressed more like someone 15-20 years younger,) but when you look properly, they look much closer to their actual age.
I have known people ask others to guess their age in real life, and if they are 43, and someone says 'early 40s?' they either get sniffy and offended, because everyone else thinks they look 26! OR they laugh and say 'no, don't be daft, come on,
how old do you REALLY think I look?' Because they find it unfathomable that someone doesn't think they look 14-15 years younger.
I also have no idea why 'how old do I look' is an AIBU either.
Same as the ghastly 'am I pregnant?' threads, where the OP posts a photo of a negative pregnancy test. What makes me roll my eyes on THOSE, is the amount of posters who say 'I see a second line! Congratulations OP!'
Also the 'am I pregnant' threads have no business being on AIBU either.