During an interview on "Good Morning America," Curt Knox said Amanda needs to be reminded to speak in English.
"It has become really almost her first language since she's been in prison so long, but she seems to be moving to English," Curt Knox said
Amanda Knox returned to Seattle on Tuesday after spending four years in Italy and has been spending time with relatives.
Curt Knox says the family is concerned about her emotional well being.
"It's a big concern of mine if there's any traumatic circumstances that arise later on," he said.
The family has not yet decided on whether to seek counseling for her.
An Italian appeals court reversed Knox's conviction in the death of her roommate Meredith Kercher, ending her 26-year jail sentence.
One of the things Amanda Knox said she would do when she got out of prison was to lay in the grass.
"She has and it's been very nice to watch her do it," he said. "It's the little things that she hasn't had a chance to do in the last four years that really make it worthwhile and really kind of get her reconnected again."
The Associated Press contributed to this report.