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Ancestor Numbers

An Ancestor Number (the proper name is an Ahnentafel number) says exactly where a direct ancestor sits in your family tree. You are always number 1. Anyone's father has double their number, and their mother double plus one: so your father is 2 and your mother 3, your father's parents are 4 and 5, your mother's parents 6 and 7, and so on. That's why every man in your tree (apart from you) has an even number and every woman an odd one.

Entering the Ancestor Numbers of your direct ancestors on My Ancestors keeps your records accurate, helps your cousins work out how they're related to you, and tells apart two lines that happen to share a surname.

Peter Calver, who founded LostCousins, explained Ancestor Numbers in his newsletter of 25 December 2023 (Why are your female ancestors odd?).

Find a number by stepping back from you

Choose father or mother, one generation at a time, until you reach the person you want.

  1. 1 You
  2. 3 Your mother
  3. 7 Your mother's mother
  4. 14 Your mother's mother's father
  5. 29 Your mother's mother's father's mother
  6. 59 Your mother's mother's father's mother's mother
  7. 119 Your mother's mother's father's mother's mother's mother
  8. 239 Your mother's mother's father's mother's mother's mother's mother
  9. 479 Your mother's mother's father's mother's mother's mother's mother's mother
  10. 959 Your mother's mother's father's mother's mother's mother's mother's mother's mother
  11. 1919 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother
  12. 3839 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother
  13. 7678 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father
  14. 15356 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father
  15. 30713 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother
  16. 61427 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother
  17. 122854 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father
  18. 245709 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother
  19. 491418 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father
  20. 982837 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother
  21. 1965675 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother
  22. 3931350 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father
  23. 7862701 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother
  24. 15725403 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother
  25. 31450807 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother's mother
  26. 62901615 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother's mother's mother
  27. 125803231 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother's mother's mother's mother
  28. 251606463 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother's mother's mother's mother's mother
  29. 503212926 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother's mother's mother's mother's mother's father
  30. 1006425852 Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother's mother's mother's mother's mother's father's father

Your mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother's father's mother's mother's mother's mother's mother's mother's father's father, a 27x great-grandfather, is number 1006425852.

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