Full sibling vs half sibling

Question

Initially one of my full siblings and I received dna results from ancestry.com. which showed that our shared dna is 1752cm, and we were matched under close family - 1st cousin. I was a little confused as this meant we are only half-siblings, so I asked another sibling to test their dna, in order to see which of us was the full sibling. However, this full sibling also came under close family - 1st cousin with 1547 cm shared.

That means the three of us may have different fathers! This can't be possible. Could these dna results be incorrect? Could we still be full siblings but only share 25% dna?

Answer 1

DNAPainter supports your conclusion of "not full siblings".

However, unless there's more here than you have told us, I think you're running ahead of the data with "three of us may have different fathers".

Let's call your siblings "S1" and "S2"

If I'm reading your post correctly, you and S1 share 1752 cM, and you and S2 share 1547 cM. That does suggest that you and S1 and S2 are half-siblings (though there are other possible relationships), but I don't see where you get to "three fathers". If you know or learn the amount of shared DNA between S1 and S2 they may be full siblings.