The false breaks are difficult to identify if you have not tested multiple generations of descendants. A person can do a basic comparison of parent-child.
A mother-child should show as sharing 23 full chromosomes / segments.
A father-daughter should show as sharing 23 full chromosomes / segments.
A father-son should show as sharing 22 full chromosomes / segments. (22 because the will not share the X-chromosome and the y-chromosome is not used in the matching.
If the segment count exceeds the numbers list above it means that the parent or child shows a break or multiple breaks. These false breaks affect the start or stop points for some matches.
I show one break with my eldest son but 2 breaks with my younger son. My wife shows 5 breaks with each son but they are not all the same breaks and some of the breaks are in our son’s Dna (I have tested 2 bloodlines 5 generations deep and 2 bloodlines 4 generations deep which has helped me to see in which person some of the breaks occur.)
In my project about ½ or 2/3 of the project members have one or more false breaks. The different testing companies and their software each handle these a bit differently. Family finder is stringent in reporting breaks, ancestry.com appears to also be stringent, 23andme is a bit more relaxed and ignores some while Gedmatch is more relaxed and ignores many of them.
Dna explained / Robert Estes has used some of my family data for her write-up about the X-chromosome
