Hi! I believe I can be of help with this issue.
First, let me say I can imagine how disturbing this situation must be for you. I have worked with teenage girls from the Ukraine and other countries in that region but this was in an invitational girls' school and they were not orphans. But their behavior was certainly not indicative of this type of training or sexual acting out. The cultural context in the Ukraine is not, to my knowledge, that different from other Western countries like the US. They are often even less forward than American teens.
The explanation that at this orphanage they watched porn videos is itself disturbing. It is only half of an explanation: not only don't we know why they would do this, which is not acceptable behavior in their society, but we also don't know what else was going on in the orphanage. It is very strange to me as a psychologist that such aberrant behavior as showing little girls pron is the ONLY strange thing going on.
So the problem you have is that there is reason to worry about what has happened to her or been done to or with her as well as her inappropriate social cues. She may very well not know that she is being sexual at all. She may be mimicking the videos only as you imply. That in itself will require a commitment from you to retrain her over an extended period of time in appropriate social responses. But you must know that if you commit to this little girl, you will need to get her professional help also in identifying or ruling out any abuse or molestation in her past. It would be irresponsible not to do so.
I wish you the very best!
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