Case Study: How Do Genes Determine Skin Color?


This case study focuses on a news story whose headline declares that a “mother is a the only black woman to give birth to two white babies.”    Students look past the sensationalized headline to discover how skin color is controlled by multiple genes and make a final judgement about whether statements made in the article are accurate.

Polygenic inheritance patterns are examined to show how skin color is quantitative.    The case also includes a short activity where students flip coins to model how alleles are inherited and what combinations of alleles (genotypes) lead to which skin color (phenotypes.)

Students can either write down answers in their own notebook or you can print  a handout for them.  The slides are intended to provide information and then a question follow-up for discussion.  This format will also allow this activity to be appropriate for beginning biology students, since the instructor can provide more direction on answering the questions.

In addition, the slide presentation could be modified to work for your classroom, just download a copy to your own drive to make changes.

Time Required:  40-55 minutes
Grade Level:  9-12

HS-LS3-2 Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, and/or (3) mutations caused by environmental factors.

HS-LS3-3 Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.