When I teach genetics, I like to pull a little trick on my students. About the time I teach them about analyzing pedigrees and about sex linkage, I show them this pedigree and ask them to figure out what kind of trait it is.

It’s a bit of a stumper. There’s the problem of variability in its expression, whatever it is, which makes interpretation a little fuzzy — that’s a good lesson in itself, that genetics isn’t always a matter of rigid absolutes. They usually think, though, that it must be some Y-linked trait, since only males (the squares in the diagram) have it at all, and no females (the circles) are ever affected.

Then I show them the labeled version, and there’s a moment of “Hey, wait a minute…” that ripples through the class. Keep in mind that even the science classes at my university contain typically 60% or more women.

It’s a truly horrible pedigree. Not only is it trying to reduce a very complex trait like “scientific ability” to a discrete character, but its assessment is entirely subjective — a point that is really brought home by pointing out that the pedigree was drawn by Francis Galton, who judged himself brilliant, and that he was evaluating his own family.

The silent tragedy here, though, is all those women judged as lacking in the characters of brilliance and scientific ability. They are rendered as nullities by the prejudices of the time — even if they had shown the spark of genius, they probably would not have been recognized by Galton — and by a culture that wouldn’t have trained or encouraged girls to do more than master needlework and laundry and household management, and would have brought them up to value the fruitfulness of their ovaries over the product of their minds.

Look at all those empty circles. I’m sure some of them had the capacity to be an entrepreneur like Josiah Wedgwood, or an eclectic philosopher like Erasmus Darwin, or a deep and meticulous scientist like Charles Darwin, or even just a successful doctor like Robert Darwin (II-4; not someone I would have characterized as brilliant, and also an indicator of the variety of abilities Galton was lumping together in his arbitrary judgments). Half the scientific potential in that pedigree was thrown away by restrictive social conventions.

That’s the kind of blind bias we have to end, and I think this Letters to our Daughters project is a wonderful idea. Stop pretending the circles are empty, and ask them to speak; color in those circles with talent. If you are a female scientist, or you know a female scientist, write in and set an example, and show the next generation of our daughters that they have a history, too.

You can read the first letter in the project now. I think it needs a few thousand more.