A number of misconceptions about genetics held by the general public stem from how people learn about it, writes Dan Koboldt at MassGenomics. For example, he notes that people are often taught that blue eyes are recessive, but it is actually more complicated than that, though blue-eyed parents tend to have blue-eyed children.
"Illustrating genetics with tongue-rolling or a hitchhiker's thumb as simple inherited traits makes the lessons more interesting and memorable," Koboldt adds. "Realistically, however, those of us who work in genetics understand that things are rarely as simple or straightforward."
Instead, he suggests following the examples put forth by John McDonald at his Myths of Human Genetics site of using cat coat traits, including length, color, and pattern. The inheritance of those characteristics has been long worked out by breeders, and can easily be seen in photographs, McDonalds says, though he adds that it would be better to see the cats themselves.
Plus, Koboldt notes, this approach avoids the whole awkward classroom issue of mistaken paternity.