Gender & Toys: Monkey Study Suggests Hormonal Basis For Children's Toy Preferences

Well this is strange... I wonder about the size of their sample: Gender & Toys: Monkey Study Suggests Hormonal Basis For Children's Toy Preferences:

When offered the choice of playing with either a doll or a toy truck, girls will typically pick the doll and boys will opt for the truck. This isn't just because society encourages girls to be nurturing and boys to be active, as people once thought. In experiments, male adolescent monkeys also prefer to play with wheeled vehicles while the females prefer dolls — and their societies say nothing on the matter.