Blog

  • Minimal viable genetic maps
    In our first blog post on what is a centiMorgan?, we talked about genetic maps. Many of the planned tools at HAPI-DNA (and all of the current ones) use genetic maps to calculate lengths of segments or to simulate segments. One of the most commonly used genetic maps (the HapMap map) contains nearly 3.4 million […]
  • How often do two half relatives share DNA?
    Following up on the last post about full relatives, the plot below shows the rates that half relatives share ≥ 7 cM IBD segments. This uses the same abbreviations as in the previous post—1C means first cousins, 3C1R stands for third cousins once removed—but all relationships are prefixed with an `h’ for half. The first […]
  • How often do two relatives share DNA?
    Close relatives like two full siblings, an aunt and nephew, or a grandparent and grandchild always share IBD segments, so they show up in testing companies’ relative matches. However, more distant relatives may not share any IBD segments. In fact, the chance that two people share DNA decreases with the distance of their relationship. This […]
  • What is a centiMorgan?
    Genetic testing companies and geneticists in general use centiMorgans (cM) to measure lengths of DNA that relatives share. Researchers have analyzed DNA from many parents and children to measure how likely a region of DNA is to recombine in one generation.