My little sister is 10 (I spend a lot of time looking after her) and I'm somewhat concerned about her behaviours and her development. She seemed pretty normal as a toddler/baby, but these odd behaviours started at around age 5.
For example, she is a very shy and anxious child but doesn't seem interested or doesn't make any attempt to interact with other children. She always stands on her own at breaktime and watches the other kids.
In social situations she is almost mute and only speaks if spoken to and usually gives one words answers. She has one best friend but she seems to use her as a crutch and can be quite possessive over her.
She is generally very immature with most things. All of the girls in her year now wear trousers instead of skirts/dresses. However, my sister still wears pinafores and refuses to ever wear trousers. She also sometimes refuses to wear knickers because she doesn't like the way they feel. She'll wear the same pair every day until my mother manages to get them off her to wash them. She gets very upset and refuses to wear any other knickers.
She gets obsessed with things and keeps asking the same questions over and over. She loves to play with cars and lego. She lines the cars up and tries to make roads and parking spaces and traffic jams.
Another thing she does is staring at her heels/back of her shoes as she's walking. She also does this to the person infront of her - she'll stare at their heels/shoes as they are walking.
Lately she is obsessed with leaded windows and doors. She'll ask loads of questions about them and has started spying on the neighbours opposite our house because they have nice 'diamond windows'. She's been doing this for months and was embarrassed when I caught her looking through the blinds in her bedroom. The neighbour has even complained :(