I don't understand the technicalities but one of the comparisons I made on GED Match tells you if your parents are related.  The result was mine weren't which I was happy about as my mother's actual ancestry was mostly Scottish and my father's mostly Irish.....so I knew that they weren't close geographically.This is very new to the masses and I can only assume like technology it will continue more popular as time goes on.  Nothing that I have been involved in has any medical conclusions.RegardsJohan From: J&K Herron via <sct-islay@rootsweb.com> To: 'Mary McCarthy' <Ree1812@aol.com>; sct-islay@rootsweb.com Sent: Wednesday, 25 November 2015, 8:19 Subject: Re: [SCT-ISLAY] DNA comparison with different testers I am not all that familiar with the DNA programes mentioned etc, but I do know that I am the fourth in line to inherit a genetic abnormality which causes brain aneurysms.  My father, his father, and his father, all died of similar conditions, my father was more easily recognised as the condition was not discovered until 1932. His step sister, and step brother also died of a brain condition. I read some information this afternoon, describing how the recessive inheritance can be carried, which is what mine is. However, one has to ask the question regarding the close relationships between many people in the 1800's.  Cousins had children with cousins, and that has occurred in my instance, on Islay, and probably with many other families as well, given the size of the tenements and crofts, and the high number of births at the time. My g grandfather was the result of cousins, my grandfather was the result of cousins, my father was then the result of cousins.  This surely would have an affect on the DNA linkages. My maternal lineage goes way back, and even then, women married brothers, sons married step mothers, step siblings, again cousins married cousins, so surely these relations would have some affect.    Does anyone know the answers?      Thanks  Kris Herron