Part A Choose your main subject. You can choose yourself, a friend, or a family member. The relatives you compare your main subject with can be parents, a parent and a sibling, two siblings, or a parent and a grandparent.

Many human traits are complex, because more than one gene controls them. As a result, there are a variety of possible traits. For example, there are several possible eye or hair colors among humans. Even with this complexity and variance, there are traits that tend to show a dominant or a recessive inheritance pattern. This table shows some common dominant and recessive traits in humans and gives the genetic abbreviation for each trait.

Dominant Recessive
Freckles present (F) not present (f)
Earlobes free-hanging (A) attached to the head (a)
Dimples yes (D) no (d)
Hitchhiker’s thumb tip of the thumb is straight when bent back (H) top of the thumb bends at a 90-degree angle (h)
Chin cleft yes (C) no (c)
Sit down with your subject and the two relatives. Decide whether they have any of these traits. If they do, determine whether they show the dominant or the recessive form. Fill in the table with your findings. Classify your main interviewee as the main subject. Label the other two relatives by their relationship to the subject.