Are you curious to gain more information about shared DNA segments on MyHeritage? In this post, discover exactly what those purple lines stand for and how you can utilize them in your family tree research.
Your My Heritage journey will also introduce you to: What the numbers on lines with purple segments signify; How to understand information that appears when hovering over segments; And, most importantly, How you can use shared DNA segments to find which ancestor you share with other genetic relatives.
How the purple lines indicate character or behavioral traits
MyHeritage DNA is one of my go-to sites for exploring my DNA matches. Most people will have hundreds, if not thousands, genetic relatives on their list of matches.
MyHeritage makes it possible to access an abundance of data about the DNA we share with our matches, with one of the most useful tools being chromosome browser, accessible directly on match pages or through its tool.
What Does Shared DNA Segment Mean on My Heritage? A Shared DNA Segment on MyHeritage means that both you and your DNA match possess identical genetic material at one copy of a particular chromosome at its location indicated on the Chromosome Browser. We all share at least one identical segment among all our DNA matches; however we may share multiple similar segments with individual relatives.
What do purple shared segments represent on MyHeritage? Purple shared segments refer to identical sections of DNA shared between you and your DNA match, while grey portions displayed on the chromosome browser represent portions that do not match up between yourselves and each other.
Are All Shared DNA Segments “Real”?
Purple segments that are longer are likely inherited by both you and your DNA match from a shared ancestor; it is possible for multiple DNA segments from different shared ancestors to overlap between partners, however.
Understand that it is possible for small, “false” DNA segments to exist even among people we are sure we share genetic ancestry with.
Use of centimorgans shared and SNP counts can provide us with some indication of whether a purple shared segment represents legitimate inheritance from an ancestor. Unfortunately, there are no absolute rules to evaluate shared segments; here are some general guidelines.
Example: Segments smaller than 6cMs are likely false leads; while segments longer than 10cMs are more likely to be “real”, or identical-by-descent segments inherited from common ancestors and considered true leads.
SNPs (single nucleotide polymorphisms) are another way of assessing shared DNA segments; this measure compares individual locations on our chromosomes to our DNA matches; the more positions where identical matches exist, the longer and more likely it is that such segments exist.
At minimum, we look for at least 700 SNPs to indicate a legitimate shared segment; more is always better, which means a 6.6cM segment with 2000 identical SNPs is more likely to contain identical-by-descent than one with only 600 SNPs.
MyHeritage DNA provides this information directly on its match profile page; in further discussions in this article, I’ll go into more depth about it.
Does shared DNA segments represent characteristics or observable traits
Shared DNA segments only indicate identical DNA that was likely passed down from a common ancestor, not how these same segments affect us physically or psychologically. Our appearance, personality traits and physical development is determined by how genes located at either copy of our chromosome respond to each other and external environmental stimuli in their responses to one another and each other.
Siblings share DNA segments identical on both copies of their chromosomes, leading them to share more visible characteristics with one another than with other relatives who share smaller segments which only match up on one copy of chromosomes.
What do the numbers in MyHeritage’s Chromosome Browser indicate? When hovering over a purple segment (Shared DNA Segment) on My Heritage, a small box appears with some large numbers displayed inside. Once familiar with their basic meanings, these details should make more sense to you.
Does MyHeritage DNA Matching Mean My Ancestor is Close? As previously discussed, the longer a shared DNA segment, the higher its probability that it came from a shared ancestor; we also know that very long segments are likely inherited from more recent ancestors.
As one moves further away from their ancestor (in this instance my daughter’s great-grandmother), the size of the largest segment decreases accordingly.
Someday when my daughter has children of her own, they will inherit some DNA that was originally passed to me from my grandmother, though the segments will likely be smaller than 100cMs.
My daughter shares DNA segments with her great-grandmother that range in size from 9-101 cMs. Smaller segments tend not to pass down to future generations while larger ones might break up into several smaller ones over time.
How can the shared DNA segment help determine your relationship to a DNA match?
As is now clear, your shared DNA segments were passed down from an ancestor who is part of your shared gene pool. By collecting and using data from shared DNA segments, a map can be made of your chromosomes.
Chromosome mapping strategies can help you pinpoint which DNA segments came from specific ancestors. Once you’ve mapped a significant portion of your chromosomes, comparing segments shared between you and those on the “map” can reveal exactly which branch or lineage of your family tree you share; and even which ancestor you share!
Conclusion
My goal in writing this post was to help you better understand MyHeritage shared segments, how they can help expand your family tree, and what the numbers mean. These shared segments can be traced directly back to our ancestors so they’re an invaluable way of uncovering more about their story.
If you have any inquiries or would like to share something interesting from your MyHeritage DNA match list, feel free to join the discussion in the comment section.
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