Animal models prove toy preferences

An Evolution and Human Behavior study says:

The percent of contact time with toys typically preferred by boys (a car and a ball) was greater in male vervets (n = 33) than in female vervets (n = 30) ( P < .05), whereas the percent of contact time with toys typically preferred by girls (a doll and a pot) was greater in female vervets than in male vervets ( P < .01).

Some people think that girls only play with dolls because they are taught to play with dolls. Those people must have never had kids. There are some instinctual preferences, as shown by animal experiments.