Five-Part Series on Visual Phasing:
- Part I – Explaining visual phasing and identifying/labeling recombination points (November 21, 2016)
- Part II – Assigning segments of DNA (November 22, 2016)
- Part III – Using cousin matches to identify which grandparent provided the segments
- Part IV – Mapping my own chromosome using the visually phased paternal chromosomes
- Part V – Using the mapped DNA with new matches
This weekend, I spoke at a meeting of the New England chapter of the Association of Professional Genealogists, and it was a wonderful group. One of my talks was about “Chromosome Mapping.” Unfortunately, since the talk was only an hour, we didn’t have time to discuss “Visual Phasing,” a chromosome mapping methodology. Instead, I promised to finish this blog post to explain the process. As I was writing, the blog post turned into a 5-part series!
- What is it? A method to assign segments of DNA to the test-taker’s four grandparents.
- Why use it? To identify which grandparent gave the test-taker which segments of DNA (eliminating 75% of the family tree to search for MRCA).
- What do you need? Autosomal DNA of three siblings uploaded to GEDmatch.
Visual Phasing is a process by which the DNA of three siblings is assigned to each of their four grandparents using identified recombination points, without requiring the testing of either the parents or grandparents. Although the process does not automatically reveal which segment belongs to which of the four grandparents, matching with cousins provides this identification as a further step of the process.