Gedmatch autosomal comparison

[francesca]

a paternal aunt has recently insisted that her father is not my paternal grandfather but his biological brother. after uploading our dna results to gedmatch, the autosomal comparison utility calculated the following:

Largest segment = 93.2 cM
Total of segments > 5 cM = 953.1 cM
Estimated number of generations to MRCA = 2.0

upon further inquiry on different forums, i discovered a person that has a half-sibling paternal aunt but the values are:

Largest segment = 62 cM
Total of segments > 5 cM = 893 cM

in addition, based on a post dated a year ago, a person with a full (same set of parents) paternal aunt shared the following:

Largest segment = 79.3
Total of segments > 5cM = 1561.5
estimated no. of generations = 1.6

would it be safe to assume that my aunt is correct based on our gedmatch comparison? unless i find someone with a similar situation to compare our results to even an educated guess would be appreciated.

[katerennie4]

She's saying that she thinks her mother is your grandmother but your grandfather's full brother is her real father? If that's the case you'd expect her and your father to share about 37.5% with one another. And you and she would share about 18.75% rather than the expected 25%.

If I'm calculating it correctly, the two of you share about 13%? If so, i'd say either she's right or more likely since she's near the 12.5% level, her father was someone else altogether. Hopefully someone else will confirm my numbers. I'm basing the approx 13% from my 3585cm to my parents on gedmatch and using that as a 50% match.

[francesca]

that is correct. my father and his sister (my aunt) share the same mother. my aunt is saying that she and my father dont share the same father. she is also saying that her father and my father's father were brothers.