January 6th is my mother’s birthday. As a present, I decided to showcase the first scientist I ever knew—one who I met before I was even born.

Arleen Garfinkle (one day to be Arleen Miller) entered graduate school  at the University of Colorado in the fall of 1973 and graduated in 1979. During that time she developed a battery of tests designed to track a child’s numerical and logical reasoning skills, based on the theories of psychologist Jean Piaget.

Once she developed the test, she gave it (and several other tests) to over 200 pairs of twins aged four through eight and correlated their success rates to other factors, such as their gender and how much their parents emphasized success. One of her most significant findings was that a young child’s ability to learn math was highly dependent on genetics. Another was that gender had no effect on performance—i.e., girls and boys were equally good at math.

Despite being offered a prestigious position at Yale University, my mother left academia to pursue other interests. But to me, she’ll always be my favorite scientist.

While I visited home for the holidays, I sat down with my mom and asked her about her research, her time as a scientist, and her thoughts on science.

Here’s the interview:

J. Let’s start with the research. Can you tell me what your goals were for the study?

A. I was interested in the heritability of the ability to learn math, because my background was in biology and math and I was interested in genetics and math.

J. Can you describe what heritability means?

A. It’s a statistical measure comparing the difference between identical twins and the difference between fraternal twins. The higher number, the more similar identical twins are than fraternal twins.

J. So it’s a measurement of how much a particular trait depends on genetics compared to the environment?

A. Yeah, but it’s a statistical analysis. You’re comparing the differences over all the pairs of twins.

J. Then this study is really trying to address the age-old question about nature vs. nurture. Is that right?

A. Yes.

J. And what would you say were the significant results of your study?

A. There was a significant heritability for the ability to learn math and logical ability in four- to eight-year-olds. But visual memory had no heritability. In addition, for this age range, there were no significant sex differences. And there was also no significant effect of age on the heritability.

J. I remember your thesis said that previous studies showed a gender difference in the ability to learn math…and that this was because those tests had introduced biases. Can you tell me a little bit about what you did to avoid bias?

A. Every child was tested [by] a male and female, so there was no potential administrator sex bias. And they [were all] trained so that they basically had a script so that every child heard the same words and directions.

J. And this was new? People didn’t do that before?

A. Apparently not. I don’t think so. Also, this is an age where sex differences don’t necessarily show up […] although other people found them. I think that’s why we didn’t find any sex differences…because we were very careful to not bias for sex differences.

J. Do you think your result and results like it help contribute to a more gender-equal society?

A. [laughs] I don’t think the general public has any knowledge of this. But if it got out there, maybe. Also, the world is evolving to be more egalitarian. This test was done forty years ago.

J. You also tested for environmental factors that influenced cognitive development. What did find there? In general terms?

A. Parental education had an influence […] on numerical and logical thinking, but not on visual memory.  Intellectual/cultural background also had an influence. Age was the most significant factor in the tests, which is not surprising at all.

J. So would it be fair to say that, as far as nature vs. nurture goes, it’s complicated?

A. Oh, it’s definitely complicated.

J. Let’s step back from the details of the research for a minute. Can you tell me why you used twins? Why are twin-studies a useful tool?

A. Because identical twins have the same genetics. Fraternal twins have (theoretically) fifty percent of the same genes. So if you compare the difference between the twins, if whatever you’re testing for is genetic, the identical twins should have a closer score than the fraternal twins. So twin studies are used to compare the difference between identical twins and fraternal twins to get a handle on genetic influence.

J. Very cool. Okay, now I want to ask you not about your research, but about you. Why did you decide to get a Ph.D.?

A. I was teaching high school math and biology, and although it was very emotionally fulfilling…I wanted something more intellectually stimulating. And I combined my interest in biology and my interest and aptitude in math. I was interested in not just “adult” stuff, but in the development of the ability to learn math, and that’s how Piaget got into the mix.

J. What about math and biology appeal to you? Why did you decide to devote years of your life to them?

A. Because I was good at math and it was fun for me, and biology is fascinating, so I put the two together.

J. Why is math fun for you? Is it a puzzle…or is there something else?

A. Yeah, it’s kind of like a puzzle. It’s a challenge and you know the answer is there somewhere…and there’s often more than one way to get the answer, which lets you be creative. I can discuss that further.

J. Please do.

A. When I went to teach math in Sierra Leone, the students in Sierra Leone in high school were taught with the old-fashioned British method where they memorized how to do something. And if you tried to get them to do it a different way to find the same solution, they couldn’t do it. Like a recipe, they memorized how to solve an equation. So my big challenge in Sierra Leone was to teach these kids how to think mathematically. Get them out of the habit of “there’s only one way to solve a problem.”

J. That sounds hard.

A. It was hard because these kids were teenagers already and they were set in their ways. But most of them got it. For them, my teaching was really hard because they didn’t know how to think mathematically.

J. What strategies did you use?

A. I don’t remember…games, puzzles.

J. While you were working towards your Ph.D., did you perceive any kind of sexism? Not necessarily from your committee or your professors, but from society or the bureaucracy of the university?

A. Hm…I don’t think so. Not that I can remember. When I was at Berkeley, where I started [my undergraduate degree], there was definitely an element of being surprised that I was a math major.

J. Surprised “good” or surprised “bad?”

A. Sex bias. All my classes were many more men than women.

J. It’s still that way in my math classes. And my female friends say that that creates an intimidating environment. Would you agree?

A. I wasn’t intimidated. I do have an experience that I could share with you. When I was a junior or a senior in a math class where you had to do proofs, I skipped a step [on an exam] because I understood it […] and my professor accused me of cheating. He said, “There’s no way you could do this without that step.” That didn’t seem sexist to me at the time, but maybe it was. It made me very angry. On the other hand, it just proved I was smarter than he was. But I didn’t think of that at the time.

J. On that note, would you have any advice for a young woman, perhaps entering college, who would like to study science or math?

A. Get to know a professor in a class you really like. You have to do well and get to know them. And they’ll be an advocate for you.

J. That’s good advice. I’ve had that experience.

At that point, the interview basically ended. Thanks, Mom! And happy birthday!