More on genetics curricular revision - Down with Dominance

On a similar topic, some bloke called Douglas Allchin advocates for biology educators to do away with that nasty old concept of dominance (see, for instance, this old American Biology Teacher article).  I think he has some good points, if you ignore his worries about reinforcing 'dualities' and inflexbility in the arenas of conflict (I'm pretty sure there would still be wars and conflict even if we taught with co-dominant genetics examples instead of dominant ones - just saying.)

For instance, Allchin reminds us that many of the most prevalent misconceptions about genetics are actually misconceptions of dominance relationships:

"...some traits are inherently more likely to be inherited than
others; dominant traits are more prevalent in the population; adaptive traits eventually
become dominant through natural selection; mutations or "abnormal" genes are recessive;
dominant alleles subdue or control recessive ones...I trust these sound all too painfully
familiar"

If these don't sound painfully familiar, I suggest you immediately find the nearest Freshperson and grill them on what they know about trait dominance (don't worry, you don't have much to lose, they already think you're crazy).

Part of the problem is that the concept of dominance doesn't have much to do with inheritance, even though that is the context in which it is invariably taught.  Dominance relationships describe phenotypic expression and as such are as complex as the physiology and development of the organism they are applied to.  They cannot be neatly explained by any kind of 'universal genetic mechanism', in the way that Mendel's laws (of segregation and independent assortment) now can.  This problem is self-evident to anyone that has tried to explain the meaning of dominance to genetics newbies and had to resort to a random assortment (pun intended) of different examples to give a sense of the many different ways that dominance relationships can arise.  To make matters worse, the technical word 'dominant' has all kinds of non-technical connotations that invite misinterpretation.

Allchin's solution is to point out that students don't actually need the concept of dominance to understand inheritance.  His specific suggestions here were:

1) Re-frame genetics curricula by starting with co-dominant examples as the 'default' type of inheritance (which at the very least would be democratic, since dominant traits are by far the minority.)
2) Use the kind of co-dominant notation used for blood-types.
3) Teach patterns of phenotypic inheritance as part of development instead of inheritance.  (I got the feeling that he meant 'molecular genetics' when he said 'development', but maybe that's because where I think it should go).

I definitely agree that genetics should start with co-dominance and incomplete dominance.  You can certainly first explore Mendel's laws with such examples without muddying the terrain with traits 'dominating' each other, and the idea neatly does away with the textbook fiction that these cases demonstrate 'non-Mendelian' inheritance.  The only truly non-Mendelian inheritance I'm aware of is organellar and epigenetic inheritance, and those topics are rarely explored in introductory classes.