It was said possibly on BBLB that when Justine's twin was pregnant, Justine experienced some of the effects in sympathy
It is said sometimes that twins have a mutual empathy or telepathy. This is somewhat hard to verify as modern communications could just lead to suggestion.
Now Justine's sister can follow Justine and pick up the cues which could lead to suggestion, but Justine is cut off from her twin.
This means, for Justine she is in a control environment and we can see if there is this telepathic link.
Mind you if Justine could communicate with her twin by telepathy, would that breach the rules about contact with the outside world ?