• Date issues
• Conflicting information
• Source quality
• Faulty conclusions

You can prevent the spread of genealogical diseases in your own family tree by running these diagnostic tests:

1. Do all the dates make sense? Did someone accidentally type 1966 instead of 1866?
   
   
2. Does the chronology for each family group make sense? Is a mom giving birth too young or too old? Is a man marrying at age 12? Are children born at least nine months apart? Is a child being born after the mother is dead? Or is a child born before its parents?
   
   
3. When you find research showing a child in his parents' family group then carried forward as an adult, do the child details match the adult information?
   
   
4. What sources did the compiler use? Did she consult original records, such as censuses, passenger lists and land deeds? Or did she rely on secondary sources—citing, for example, "World Family Tree," "Aunt Susie's notes" or "Uncle Ted's GEDCOM file"—that might regurgitate erroneous information?
   
   
5. Does biographical information seem exaggerated and too good to be true?
   
   
6. Are conclusions faulty? Has a compiler misinterpreted a document because she doesn't understand the legal terms for a particular time period? What information is the compiler basing a parent-child relationship on?