Is thrulines always accurate?

[Meelystar]

So I know the basic principals of thrulines and have found it to be useful, though at times I’ve been surprised at what it doesn’t pick up.  I also understand that if multiple people have researched wrongly and put an incorrect ancestor in their tree it will suggest this likely ancestor to you.

So a pretty specific question.
Has anyone had experience of a DNA match not being related in the way that thrulines predicts? (Discounting incorrectly researched trees)

I have a low match (7cM), thrulines shows the connection to be a great x 4 Grandfather. The match and I don’t have any shared DNA matches. The match only has 10 people in her tree. 
Do thrulines rely solely on ancestry trees for their ‘predictions’ or would they also look DNA matches that she has also?

I presume it is possible that we could be connected elsewhere? I think I know the answer to this

The reason I am so interested in this specific match is that my Great x 4 Grandfather was really a putative Father, he appears on a birth certificate but after that nothing, that and various other circumstances made me doubtful he was the father.  But according to thrulines he is (should note that I have checked out with what names she has and it is a pretty straight forward match up this man)

What do others think? Sorry for the waffling 

[Gadget]

I tend to use Common Ancestors more than ThuLines and I've had a few wrong links. I share DNA with them but not as Ancestry suggests. 

[Meelystar]

Well that’s what I’m wondering. Don’t relish the thought of trying to research their tree though to find a potential additional link (mostly because I want this one to be right!)

[Pheno]

It quite clearly says that  Thrulines uses Ancestry trees to suggest links so if someone else's tree is wrong then thrulines will be wrong.

I have several where there is a dna match but not in the way Ancestry suggests so I check out the linked match's antecedents to make sure it fits, one recently had missed out a complete generation.

Pheno

[Meelystar]

Yes I understand that if a tree is wrong it will be wrong in thrulines I put that in my post 

[Pheno]

Don't quite grasp your question then sorry.

Ancestry is confirming a dna match with someone through an image of how you might be connected but the thrulines tree in which it displays this connection is quite likely to be wrong as only based on other trees with no relevance to dna.

Pheno

[Meelystar]

I’m asking if ancestry also bases their thrulines on other DNA matches that my DNA match shares (unrelated to my own) that link to the specific ancestor that could potentially be shared.

I’m also asking if others have found thrulines to be wrong because it has grasped onto the wrong branch of your tree when in fact the DNA link is to be found else where, perhaps an ancestor that does not appear on any Trees for example.

Thrulines does not just link to ancestry trees with no DNA data attached, it also links in to trees which are linked to other peoples DNA that matches your own. That does not make them accurate of course but if you believe your own tree to be correct and well researched and you share a common ancestor plus a DNA link with a match then you can reasonably assert that you have a proven DNA connection with your ancestor!

[brigidmac]

I've had thru lines offering me two potential connections

And I've had someone with quite a small cm match who comes up as second cousin once removed the names are right but I think she's missed out a generation on her line or attached her DNA with her father as home person on tree

Some of the people who should show up on thru lines are because they've added alternative spellings to each profile ..or used nicknames instead of full names
Alternative spellings really skew thru lines

[Meelystar]

That’s interesting.
Can you expand on your first comment. Do you mean two connections within different branches of your family connecting to the one DNA match?