Connection finder says 18 degrees but it is certainly rather closer; her 4th great-grandfather is Samuel Willett (my 1st cousin 6X removed), who has an unmerged duplicate profile (Samuel Willett's wife was Mary Dant whose grandfather John Dant is my 7th great-grandfather; we're also certainly related through Mills and Abell, so at least 7th cousins on two different lines, 8th cousins on another and several other relationships).
On edit, had to work it out manually, 15 degrees. 0. Me > 1. my mother > 2. Daniel S. Childs (her father) > 3. William S. Childs (his father) > 4. Daniel S. Childs (his father) > 5. Daniel B. Childs (his father)> 6. William Childs (his father)> 7. Mary Willett (his mother)> 8. George Willett (her brother)> 9. Samuel Willett (his son)> 10. Louisa Willett (his daughter) > 11. Martha Mills (her daughter) > 12. Mamie Cusic (her daughter) > 13. Amanda Hays (her daughter) > 14. Harold Smith (her son) > 15. Cheryl (Smith) Hess
And also 15 degrees another way: 0. Me > 1. my mother > 2. Daniel S. Childs (her father) > 3. William S. Childs (his father) > 4. Daniel S. Childs (his father) > 5. Sarah Ann Mills (his mother)> 6. Stephen T. Mills (her father) > 7. Charles Mills (his father)> 8. Joseph Aloysius Mills (his brother)> 9. Samuel Lewis Mills (his son)> 10. Joseph Abell Mills (his son) > 11. Martha Mills (his daughter) > 12. Mamie Cusic (her daughter) > 13. Amanda Hays (her daughter) > 14. Harold Smith (her son) > 15. Cheryl (Smith) Hess