Some ageist observations.
After three years of grunts, ignoring anything about people, like the ones that were feeding, supporting, and caring for her, at fifteen the girl started speaking in whole sentences, and treating her mother and I like we were real, and she liked us. Eye contact, smiles, cheerful voice, became part of the household.
We discussed having her evaluated, put on drugs, but after the laundry, she did the dishes, so we decieded to wait and see.
For a short time both girls were a joy to have around. Then the younger hit thirteen, and grunted.
The older babbled away for five years, and then at 21 was replaced by a stranger who understood, work, money, politics, and being the support for others. Five years later she has not changed.
The younger is starting college, She does not let people smoke in her house or car, and thinks nothing of rearranging anything.
There is a personallity difference, but not enough, they are ganging up on us.
I see that any male of 18 might just become aware of people besides himself, do to sexual drives.
Girls like people who ask their name, then use it repeatly, I do it, for forgetting is very bad. Just calling one of the sisters by the other's name is unforgivable. You remember her name, and want to know everything about her, because she is the most facinating person you have ever met. You will listen as she talks about herself, and act like it is serious and important, if you want to learn any of her deeper secrets.
In five years you may actually wonder what your parents do for a living, and how their life was growing up, what they want to do, and be an adult talking with adults.
Fifteen years of talking at children, five talking with them, and then talking to another person.
You are doing just fine.