So your sister’s DNA profile was shared around the world? Seems imprudent.
I don’t know how it works, but I don’t think it is “shared”. I think people (who consent in advance) will be notified when DNA matches are identified among the subscribers.
I have no idea whether these services (Ancestry.com, 23 and Me, whatever others) share DNA results among each other? Or limit their matching results to only their own customers.