It's briefly mentioned in the article as a possible indicator of toy preference because it correlates well with hormone levels. It clearly wasn't what the research, the discussion, or any of my comments were focusing on.
It's reported in all of the child studies discussed in TFA. Fault the article if you want but "hormones" is in the title, and the whole point of the entire line of research is that it's implausible that prenatal hormone levels could be affected by cultural biases.