I don't have scientific data, but what I know and what I was told earlier on is that when a child comes into your home, it takes double the time of the child's age. When my children came into our home, to be solidly attached.... Our children were eight, 11 and 13. For some of them, it was very difficult at the beginning to truly attach. I don't think we needed the 13 years for our 13-year-old. She's 24 and she's solidly attached, and so are all of our children. However, it does take time, because we have to repair the loss of attachment that they've been robbed off. They have lost a lot of people in their lives, so it does take a significant amount of time.