Her sister - in - law is the late track star Florence Griffith Joyner .
Joyner - Kersee is the heptathlon world record - holder and American record - holder in the long jump .
Joyner - Kersee 's sister - in - law is the late track star Florence Griffith Joyner .
Joyner - Kersee is the heptathlon world record - holder and American record - holder in the long jump .