Anyone have experience with sibling DNA tests?

[TheCampingDevil]

NC for this.

Where the father isn't available - are they reliable? Brother and I would like to know if we're full or half but no chance of getting "father" to do DNA.

Also are they all this expensive?

How about ancestry dna?

You will get a probability, but you won't get an absolute answer. So for a parenthood test it is possible to definitely exclude someone from being a parent. For siblings, alleles are inherited from parents at random, so full siblings might be expected to have a certain amount in common, and half siblings less, but it will vary from family to family.

Will you have a sample of the maternal DNA?

Thanks for the responses - hadn't considered ancestry.

No maternal DNA - was reading about sibling index levels indicating full or half siblings?

Yes, an indication is correct. It won't prove it or disprove it. I don't know how they report the answers, may vary between providers. but likely, 'these results are more consisent with being full siblings than half sibings' (or vice versa.) It's a statistical test.

So to answer your question, are they reliable? The chemistry and the statistics are well known and have been used for decades in criminal cases - so reliable in that respect.

Are they conclusive? No. That's not a con, it's because DNA is inherited at random from parents. It would be possible, although highly unlikely, for two full siblings to have no genetic markers in common.