Our faulty assumptions become clear when viewing other societies. For example, in the former USSR, 58% of engineers were women. In China, 40% of engineers are women, where less than 47% of the population are women. The communist countries placed a greater emphasis on gender equality in workforce. Sharp differences between west and the east are evident in other occupations such as medicine.
In the study cited, the mean age of the babies (neonates) was 3 days. That's enough time for babies to be influenced by adult interactions. Babies have been shown to be handled differently by adults based on their gender. Female babies are spoken to more, whereas male babies are handled more.
In the study, a substantial number of babies exhibited behaviors associated with the other gender. I would resist talking about a real sexual dimorphism when gender is not determinative of social vs mechanical preference.