You Don’t All Share the Same Bits

Analyzing DNA matches can sometimes be confusing. One issue is the bits of shared DNA that get passed down through the succeeding generations of the family. The visual with my ancestor Erasmus Trautvetter’s simplifies the genetic process, but serves to illustrate what potentially could happen.

Among all the DNA Erasmus had in his body, let’s focus on two chunks: chunk 1 and chunk 2. Only chunk 1 is passed down to son Henry. Chunks 1 and 2 are passed down through son George and chunk 2 is passed down through daughter Ernestine. Henry passes chunk 1 to one of his descendants. George’s chunk and 2 are passed down through several generations until another George. The second George passed chunk 1 down to all of his descendants, but I am the only descendant of the second George who got chunks 1 and 2. Ernestine passed down chunk 2 to one of her descendants.

For that reason, all of us in the current DNA are not matches for each other. Those of us with chunk 1 all match. Those of us with chunk 2 all match. But the descendants with only chunk 1 in their DNA will not see the descendants with only chunk 2 in their DNA.