| 100% | BUSH | 4 | Last name of father-and-son US presidents |
| 76% | STILLER | 7 | Last name of Jerry and Ben, acting father and son |
| 76% | ARKIN | 5 | Last name of father-and-son actors Alan and Adam |
| 76% | GRIESE | 6 | Last name of father-and-son quarterbacks Bob and Brian |
| 73% | ALDA | 4 | Last name of father/son actors Robert and Alan |
| 70% | MORA | 4 | Last name of father-and-son N.F.L. coaches |
| 67% | ONEAL | 5 | Last name of father-and-daughter actor Ryan and actress Tatum |
| 67% | MAHAL | 5 | Last name of father-daughter singers Taj and Deva |
| 67% | HARRISON | 8 | Last name of two U.S. presidents |
| 66% | BUSH | 4 | Last name of two US presidents |
| 66% | ADAMS | 5 | Last name of two early US presidents |
| 65% | BOHR | 4 | Family name of father and son who won 1922 and 1975 Physics Nobel Prizes |
| 65% | TAFT | 4 | Last name of 27th US president William H |
| 65% | PIERCE | 6 | Last name of 19th-century US president Franklin |
| 64% | BUCHANAN | 8 | Last name of the 15th president of the US |
| 64% | ADAMS | 5 | Last name of two of the first six US presidents |
| 63% | KENNEDY | 7 | Last name of last U.S. President to die in office |
| 62% | ROOSEVELT | 9 | Last name of Presidents Theodore and Franklin D. (they were distant cousins) |
| 60% | ALI | 3 | Last name of father-and-daughter members of the International Boxing Hall of Fame |
| 57% | ASSAD | 5 | Name of father-and-son world leaders |
| 55% | ADAMS | 5 | Last name of two presidents |
| 55% | BUSH | 4 | Last name of two presidents |
| 54% | OBAMA | 5 | Last name of Sasha and Malia |
| 54% | BAGGINS | 7 | Last name of Frodo and Bilbo |
| 54% | ALI | 3 | Last name of boxers Muhammad and Laila |
| 54% | OBAMA | 5 | Last name of teenagers Malia and Sasha |
| 54% | BABBITT | 7 | Last name of 30- and 35-Across |
| 54% | COEN | 4 | Last name of filmmakers Ethan and Joel |
| 54% | GALLO | 5 | Last name of winemakers Ernest and Julio |
| 54% | COEN | 4 | Last name of filmmakers Joel and Ethan |