Older Child Adopt-Do they ever really love you?

I have four children adopted from foster care, home at ages 5,9,10, & 14. They have never spoken to me like that. Neither have my other birth children. Three of my kids are grown and out, one more graduating soon. We have had plenty of teen and preteen angst, hormones, we've had RAD, step family situations, have dealt with all sorts of issues. They have talked back plenty. They have been disrespectful. But they have never gone anywhere near that extreme. They do seem to love us very much, and they are loved deeply as well. This behavior is very disturbing to me, and I would have the child in counseling. She has no concept of boundaries or respect. Did she used to act much better??? Something seems very wrong and worrisome, I hope you get some help and things get dramatically better.