Joanna has "short fingers" (brachydactyly). she has two older brother who are identical twins; both have short fingers. joanna's two younger sisters have normal fingers. joanna's mother has normal finger, and her father has short fingers. joanna's paternal grandmother (her father's mother) has short fingers; her paternal grandfather (her father's father), who is no deceased, had normal fingers. both of joanna's maternal grandparents (her mother's parents) have normal fingers. joanna marries tom, who has normal fingers. joanna and tom produce two children: an older daughter with short fingers and a younger son with normal fingers.