> “This is a very well-designed study that validates the notion that sex differences start early in development—and that they depend on the sex chromosomes because that’s the only thing that can account for those differences,” says Nora Engel, a professor of cancer and cell biology at Temple University, who was not involved in this work.
There's two problems here. One is that XX/XY is not even a majority of the common human chromosome karyotypes, and changing karyotypes does not change someone's sex characteristics; those are determined at one specific moment during gestation, which may or may not be affected by changing the chromosomes beforehand, but certainly would not be affected by changing their chromosomes after that moment. Primary and secondary sex characteristics are determined by androgen metabolism, not by chromosome karyotypes.
Secondly most of the human karyotypes are not assigned a sex until some time after birth, and XY is often assigned female at birth because the divergence of homologous structures depends on androgen metabolism, not chromosome karyotype. Sex and gender don't exist for cell lines in the same way they do for people.
TL/DR; This is an article about a study that found they could change a cell line's karyotype, not a person's sex characteristics which are determined not by chromosome karyotypes but by androgen metabolism during gestation. Whoever wrote the headline didn't understand the topic.
> “This is a very well-designed study that validates the notion that sex differences start early in development—and that they depend on the sex chromosomes because that’s the only thing that can account for those differences,” says Nora Engel, a professor of cancer and cell biology at Temple University, who was not involved in this work.
Is this your area of expertise?