12 Common Genealogy Mistakes and How to Avoid Them

The most frequent errors in family trees, from same-name confusion to copied online trees and impossible dates, with practical ways to catch and prevent them.

Every experienced genealogist has a tree they built in their first year and later had to take apart. The mistakes below are the usual culprits. Knowing them in advance saves you the rebuilding.

1. Attaching the wrong person with the right name

Two men named Jan Kowalski born in the same parish a few years apart is normal, not rare. Before you attach a record, check that the parents, the spouse, the residence and the occupation match what you already know. When two candidates fit, record both as hypotheses and keep looking.

2. Copying other people's trees

Online trees are where mistakes go to multiply. Use them as hints, then find the original record. If you cannot find it, mark the link as unproven.

3. Impossible dates

A mother aged 9, a child born after the father's death by three years, a marriage before the birth of the bride. Most programs can run a sanity check; run it every month. A printed chart also exposes these instantly, because the years stand next to each other.

4. Assuming the surname was always spelled that way

Clerks wrote what they heard. Kowalski, Kowalsky and Kowalskie can be one family. Search with wildcards and read our article on surname variations.

5. Ignoring the mother's line

Half of your ancestors are women, and their maiden names appear in baptism and marriage records. A tree with only the male line is half a tree.

6. Trusting a single source

A gravestone carved years after the death, a census age rounded to the nearest five, a family story told three times. Look for a second, independent source before you call a fact proven.

7. Not recording sources at all

The most common mistake and the most expensive one. Without citations you cannot resolve conflicts, and nobody after you can verify your work. Cite as you go.

8. Merging duplicates carelessly

When two records for one person are merged, the wrong one sometimes wins: a wrong birth date or a wrong spouse survives. Compare field by field before merging.

9. Skipping the siblings

Siblings are how you distinguish families with the same name, and their records often name the parents when your ancestor's own record does not. Record the whole family, not just your line.

10. Guessing the place from the modern name

Villages were renamed, merged and moved between countries. Record the place as it was written in the record and add the modern name in a note.

11. Filling gaps with placeholders

Unknown, Mrs Smith, 1 Jan 1850. Placeholders look like facts on a chart and in a book. Leave fields empty and use ABT for estimates; see missing dates.

12. Never printing

A tree that lives only on a screen is reviewed only one person at a time. Print a chart, put it on the table at a family gathering, and let twenty pairs of eyes find what you missed.

The habit that prevents most of them

Prove each generation before you move to the next, write down where every fact came from, and look at the whole family on a chart regularly. Slow and documented beats fast and famous every time.