Closing chromosomes...
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Warning: This is an unsaved tree. If you want to make edits, please click 'Save' below

What Are the Odds? Read the FAQ

Target name: Enter the name of the person you're trying to place in the tree Birth year: YYYY

My research question is: Enter the question you are trying to answer here

The file you loaded was imported successfully


Tree deleted


This is an example tree. Create a new tree by clicking here

You are viewing this tree in read-only mode. If you would like to make edits, please click Save and make a copy in your DNA Painter account first.


You can now import a GEDCOM (family tree) file into WATO. Click 'Import GEDCOM' below and select your file. You can then select a person from the tree and the site will extract all their descendants.

Important: this will overwrite everything currently in this tree!

Please select a valid file
(only text files downloaded from this tool will work!)

Or: browse for a tree data file saved from WATO

This is a text file; only a file downloaded from this tool will work

Important: this will overwrite everything currently in this tree!


If you'd like to save this tree to your DNA Painter account, please sign in or register (free).

Experimental: you can save an image of this tree. The results may vary according to your browser. For the best results, try to maximize the size of the window before clicking this button. This feature works best in the Chrome, Firefox and Safari browsers.

You can also download the data for this tree locally and load it back into the tool later (or send it to someone else so they can load it in).

To do this, click the button below.


If you'd like to share a link to this tree you need to save it first.

Please click 'Save' and then 'Save tree' and try again.


You can delete this tree. This action cannot be undone


Tree orientation

Background colour of saved images

You have hypotheses that are not mathematically feasible

Click on any score to show match relationships

View score calculation View ranking of hypotheses

Hover over a person for options. Scroll to the right to see children.

Suggesting Hypotheses

Click to add notes

Ranking of Hypotheses

After you've added matches and hypotheses to a tree, hypotheses will appear here.

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Score calculation

This table shows the following for each match:

  • Amount of shared DNA in cMs
  • The genealogical relationship with each hypothesis based on its position in the tree (for example 3rd cousin)
  • The probability that the amount of cM shared corresponds to this relationship

These individual probabilities are then used to calculate the combined odds ratio used for the score

If a probability appears in red as '0.00%', this means this relationship is not statistically possible given the shared cM amount you've entered.

The odds ratios are made by comparing all hypotheses that are considered possible and then determining the relative likelhood of each. For more information please see the FAQ.

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View ranking of hypotheses Back to top

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About this tool

This tool has been built to help solve DNA puzzles (including unknown parentage cases) by undertaking the calculations described by Leah Larkin in her series Science the heck out of your DNA...

© DNA Painter 2018-2022


Due to the lack of statistical data available, this tool has limited applications to the following scenarios:

  • Double-cousin relationships
  • 3/4 sibling relationships
  • Matches with endogamous ancestry


WATO uses probabilities simulated by AncestryDNA and originally described in their White Paper.

The underlying calculations that convert the compounded probabilities into the odds ratio used for the score were developed by Dr. Andrew Millard.

Valuable advice on the user interface and functionality was provided by Mike Mulligan. Many thanks also to the early beta testers from the GG&T group on Facebook.

The static tree layout was adapted from an example by Peiwen Lu.