I used to be one until I fell pregnant at 26 and put on 3 stone!
From a young age I was a bean pole, same height as my mum by 13, 5'9 by 16. No shape to me, no breasts, noticeable ribs. I ate healthy, small portions but then I ate very slow at that age and became full before finishing a meal. Went in to my 20's very similar but with boobs and hips, hovered around 9st to 9.5 size 8-10. Lowest weight was 8.5st which even I recognised as too low so increased my diet to put the half stone back on. Happy, healthy, no medical issues, active.
People would try and diagnose me with something though. I was accused of being bulimic, anorexic, having an overactive thyroid. Women would suggest I was too skinny to be fertile and that I would struggle to have kids, suggestions of going to the doctors, did I suffer with depression, did I hate the way I looked. Was constantly referred to as the skinny one, she's all skin and bones her, needs to eat more, looks unhealthy. And this would mainly be from women. I very infrequently had men comment on my size.
To be honest, I ignored most of it, became used to it. But sometimes I just wanted to stand there and shout its not my fucking fault! Genetics played a big part, both grandparents are slim and have never seen anyone in my family look overweight.
Sure, I'm no 'skinny minny' anymore. My weight is around 10.5st so relatively slim in size 10-12. I'd love to get back to 9.5st though. I felt happiest at that weight.