Read me
This simplified diagram shows eight chromosome pairs rather than the usual 23.
Each thin bar represents one copy of a chromosome. You carry chromosomes in pairs, with one copy
inherited from your mother (top) and the other from your father (bottom). The colours show which
earlier ancestor contributed each stretch of DNA. When egg or sperm cells are formed, the two copies
in each pair exchange DNA at a small number of largely random crossover points, creating a new
recombined chromosome. Because nearby genetic markers tend to be inherited together, DNA usually
passes from one generation to the next in blocks rather than gene by gene.
The real picture
Each panel shows the chromosomes of one great-grandparent, identified by a different colour. Turn the crank to follow how their DNA is recombined and passed through the generations to you. 50% from each parent — always
Trace an ancestor
Click any great-grandparent, or the corresponding colour below, to highlight the DNA inherited from
them and see the total percentage. Each great-grandparent contributes 12.5% on average, but
recombination means the actual percentages can vary, as this example shows.
Read me
Each ring represents one generation and each cell represents one ancestor. The percentage shown is the
proportion of your autosomal DNA inherited from that ancestor in this simulation. Ancestors from whom
you inherited no autosomal DNA are shown in hatched grey. The coloured lines mark the direct
mitochondrial, Y-chromosome and X-chromosome inheritance paths.
The vanishing ancestors
Choose the number of generations and run the simulation to see how much autosomal DNA you inherited from each ancestor.
Simulating a
Autosomal DNA inherited (deeper blue = more)
No autosomal DNA inherited
Every ancestor accounted for
One row per ring of the wheel. In each row the two counts add up to the total number of ancestors in that generation, so the figures and the picture always agree. The final row adds every ring together — the whole wheel, inner rings included.
What "vanishing" means
These ancestors have not vanished from your family tree. They are still your ancestors and the line
of descent still runs through them. What has vanished is their detectable autosomal DNA:
none of it survived the shuffling of recombination along this particular simulated path down to you.
Mitochondrial DNA
follows the direct maternal line. At each generation, one ancestor lies on that line, although you
may inherit no autosomal DNA from her.
Separate paths
The mitochondrial, Y-chromosome and X-chromosome lines are separate inheritance paths through the
same tree. They are drawn on top of the wheel and never change the counts above: an ancestor on one
of these lines still counts as contributing no autosomal DNA if none reached you.
Honesty note
Every percentage and count on this page is computed live from the simulation shown, not hardcoded.
The model is simplified — eight representative chromosomes with realistic relative lengths and
an approximate crossover rate (Poisson ∝ length, ≥1 per chromosome; female meiosis set higher
than male). It teaches the real shape of the phenomenon without claiming per-person precision.