Middle School Students’ Reasoning about Biological Inheritance: Students’ Resemblance Theory

This study investigates middle school students‘ reasoning about biological inheritance via examining students‘
responses to online curricula scaffolding support prompts. A total of 250 seventh-grade students participated in
the study and completed a web-based unit on genetics. Students‘ responses to these prompts were examined to
determine whether students held the conceptions about genetic inheritance commonly reported in literature, in
addition to being scored for scientific accuracy. Where possible, attempts were made to identify whether students
were using evidence from the instructional materials or from their out-of-school experiences in their responses to
the prompts. It was evident that approximately half of the students considered traits of offspring to be inherited
directly and solely from whichever parent they resemble for that characteristic, rather than viewing it as the
result of the interaction of alleles contributed equally by both parents. The term students‘ resemblance theory
was used to refer to this conception. We argue that students‘ resemblance theory may be used to explain
students‘ thinking when they incorrectly believe that same-sex inheritance of characteristics (e.g.,
mother/daughter or father/son) to be more prominent. Specifically, we argue that students‘ resemblance theory
may influence students‘ learning and understanding of Mendel‘s Law of Segregation.