Thrulines suggesting half-sibling relationship

[mijath]

Hello, attached is a suggested relationship between myself and a DNA match - we share Susannah as a 3xgreat grandmother.

(The DNA match's tree ends at Mary while mine goes back further to Susannah and beyond)

Thrulines is suggesting that my ancestor Robert and his sister Mary were half-siblings. Is this based on the fact that our shared DNA is less than would be expected for two people sharing a 3xgreat grandparent, with the same number of generations between?

I have suspected Robert and Mary were not full siblings, should I take this as the best evidence I'm likely to get?

Thanks for any guidance

[Pheno]

No don't take this as definitive evidence of half siblings.

Ancestry only gets this info from other people's trees so if they have it wrong so does thrulines.  It can be something as simple as a difference in spelling/dates on the other tree meaning that the Ancestry algorithm assumes they are different people.

You need to study the other tree if it is public to determine how factually correct it is and what evidence there is.  Sometimes they have the wrong family attachments and muddle mothers and daughters etc.

In almost every case that Ancestry have suggested half siblings to me I have been able to prove otherwise.

Do not take thrulines as evidence.

Pheno

[frostyknight]

I agree with Pheno. Don't take Trulines as evidence of a relationship. I've had "half" relationships show on one of my lines too. Why? Because one of the trees Anc used for Trulines has the wrong parent for someone. Best to check everything yourself.

[larkspur]

I have a named  father for my great grandad on thrulines from the info on 10 different trees. He was illegitimate. I have his birth certificate and baptism naming just his mother, ( They have the same surname) and his marriage certificate with no father listed. It is annoying, but nothing I can do, as the owners of the 10 trees will not reply to messages or change the correct info I enter as a comment on great grandads profile page.