The abstract of link [4] says the following:
> Gender differences were found [] due to an increase in girls' gaze behavior. Girls also made more eye contact in female–female dyads and in the second interaction over the first. Boys' behavior remained unchanged over time. The data provide evidence for gender differences in mutual gaze in a younger sample and wider context than previously demonstrated.
This seems to reinforce the claim that there are gender differences, doesn't it? (I don't have access to the full paper and can't see the result you're referring to)
> This difference starts at a young age, with boys receiving more functional toys that develop logic and hand eye coordination, while girls receive more dolls, dollhouses, stoves, strollers, etc.
Did you know that a monkey research study examined toy and play preferences of male and female monkeys? Like humans, male adolescent monkeys prefer to play with wheeled vehicles, while the females prefer dolls. "Sex differences in rhesus monkey toy preferences parallel those of children" [7]:
> Sex differences in juvenile activities, such as rough and tumble play, peer preferences, and infant interest, share similarities in humans and monkeys. Thus if activity preferences shape toy preferences, male and female monkeys may show toy preferences similar to those seen in boys and girls. We compared the interactions of 34 rhesus monkeys, living within a 135 monkey troop, with human wheeled toys and plush toys. Male monkeys, like boys, showed consistent and strong preferences for wheeled toys, while female monkeys, like girls, showed greater variability in preferences. Thus, the magnitude of preference for wheeled over plush toys differed significantly between males and females.
[4] http://link.springer.com/article/10.1023%2FB%3ASERS.00000110...
[7] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2583786/