I too have experienced this, via Genes Reunited after replying to a contact without realising that permission to view your tree is automatically selected, and that you have to deselect it yourself.
I thinnk this is wrong, and that you should have the option to enable them to view...it should not be automatic.
The person who pilfered my tree is nothing more than a name-collector, with in excess of 24,000 ‘ancestors’ in his tree. He contacted me initially over two years ago when I was just putting together my first attempt at the family tree, and before I knew it, thanks to the inadvertant access he'd been given, he’d incorporated all of my information into his tree, even the likes of my grandfather’s parents….who are of no biological link to him at all, as his 'link' is on my grandmother's line.
His ‘link’ to our line is at best remote, with the link being something like ‘his aunty was the three times removed cousin of my Great, great, great grandmother'.
Ridiculous.
Furthermore, recent discoveries I’ve made would even seem to cast doubt on this link, as I have discovered that there were two people of the same namem from the same area, born within 5 years of each other, both with similarly named siblings and both with fathers of the same name and trade. My ancestor's death record indicates she’s the older of the two, but her age on all other records ties in with the younger one.
As such, there really is no way of determining which of the two families our lot descend from and their supposed link predates this. So, as far as I am concerned, my direct line ends there, until such time, if ever, that we are able to verify which person is ours.
Another name-collector now seems to have inherited this information too, with another who's link is also very remote. This person seems to just link any information sharing a same name together. For instance, he seems to think that one of my grandmother’s aunties died in America! I know she didn’t, as I’ve found her grave…
If that's their bag, fair enough...I've done some serious research on certain lines, and it would seem more so than most others who are researching them, which gives me a buzz in turn!
As such, the internet is now full of very basic, of out-of-date and mutated information that came from my tree in the first place, and is of no use to anyone really!
I am now more careful about who I pass my information on to, but am happy to do so where a valid, no-so distant link is clear.
Paul