Anonymous wrote:OP here, thanks for putting it in perspective. It may be anxiety (her dad has anxiety) and I suppose she could be on the spectrum (her grandfather is). Let's say she has social anxiety or general anxiety--would it still be appropriate to try and force her to respond to people? I often repeatedly try to get her to respond, but most of the time she doesn't. I don't know if it matters, but she does have some close friends, and is a little chatterbox with them!
Being a chatterbox with close friends and family and being anxious around others is totally normal. I have no idea why you equate this with being a "mean girl."
Rather than forcing her to interact, coach her every time about what she should do or say in the moment. At other times, perhaps practice things she can say when someone says hi or wants to play -- talk about it but also role-play so she can practice saying it. It can be helpful for kids to have a script.