San Jose State Biology Professor: 'Chromosomes Don't Determine Sex'

San Jose State Biology Professor Rachael French argued in a tweet this week that “chromosomes don’t determine sex.”

San Jose State biology professor Rachael French has come under fire this week for a tweet in which she claimed that “chromosomes don’t determine sex.”

“Hey geneticist here. You’ve disingenuously and for bigoted purposes oversimplified a complex phenomenon,” she wrote. “A few notes: 1) Sex and gender aren’t the same thing. 2) Chromosomes don’t determine sex,” French wrote in response to a tweet by Republican State Representative Briscoe Cain.

“I know high school biology told you they do, but nope,” she added in a follow-up tweet. “A single gene on the Y starts a cascade of events involving genes all over the genome to determine sex. If any of those things changes, surprise!”

French’s San Jose State University profile shows that she does research on cellular response to alcohol exposure.

My lab uses the common fruit fly Drosophila melanogaster to study the genetic and molecular mechanisms mediating the cellular response to alcohol exposure. I have established a Drosophila model of fetal alcohol syndrome. My current research focuses on using this model to identify the neurodevelopmental pathways that are altered by exposure to alcohol during development, and the genes underlying those pathways. Understanding these pathways may lead to future therapeutics to treat fetal alcohol syndrome.

French doubled down on her claim on Thursday, in a tweet that disputed a claim made by Campus Reform that they reached out to her for comment prior to publishing their report on her “chromosomes” claim.

According to science educator Regina Bailey, chromosomes are responsible for determining a large number of human characteristics, including sex.

Chromosomes are long, segments of genes that carry heredity information. They are composed of DNA and proteins and are located within the nucleus of our cells. Chromosomes determine everything from hair color and eye color to sex. Whether you are a male or female depends on the presence or absence of certain chromosomes. Human cells contain 23 pairs of chromosomes for a total of 46. There are 22 pairs of autosomes (non-sex chromosomes) and one pair of sex chromosomes.