Boys are genetically programmed to prefer Bob the Builder to Barbie dolls, say scientists. Tests involving children as young as three months suggest biological differences and not social pressures dictate which toys children like to play with. The U.S. study looked at babies aged three to eight months - before they can identify even the gender of other people. Researchers placed a doll and truck inside a puppet-theatre style box and showed them to 30 children - 17 boys and 13 girls - for two ten-second intervals. The findings, from researchers at Texas A&M University, overturn conventional wisdom that childrens toy preferences are down to social conditioning. The academics believe that societys expectations do play a major part in influencing how children play. But subtle cues from parents and peers merely reinforce a pre-disposition for masculine toys among boys and feminine for girls. One theory is that these innate preferences are linked to traditional male and female functions dating back to the dawn of the species. Boys are thought to prefer playing with cars and balls because they involve moving objects and rough and tumble play. These activities may be linked to their ancestors skills in hunting for food and finding a mate. Girls, on the other hand, are thought to like red or pink toys because a preference for those colours enhanced their abilities to nurture infants, thus aiding their familys survival. For the study, led by Gerianne Alexander, researchers set up a presentation box similar to a puppet theatre and placed a doll and truck inside. Eye-tracking technology measured how many times and how long the babies focused or 'fixated on each object. The researchers found that 'girls showed a visual preference for the doll over the toy truck and boys compared to girls showed a greater number of visual fixations on the truck. The study, published in the Archives of Sexual Behaviour, added: 'The findings from the present research are consistent with the hypothesis that males and females may show different patterns of attention to toys because they are attracted to different visual characteristics of objects. 'It seems unlikely that object interests in infants younger than nine months of age are a result of internal motivation to conform to external referents of gender role behaviour. It is believed that exposure to sex hormones in the womb has a bearing on toy preferences, as it does many other aspects of gender-related behaviour. DM The study reinforces the findings of previous research by Dr Alexander involving green vervet monkeys. Male monkeys spent more time playing with traditional male toys such as a car and a ball than did female monkeys. The female monkeys, however, spent more time playing with a doll and a pot than did the males. Both male and female monkeys spent about the same amount of time with 'gender neutral toys such as a picture book and a stuffed frog. Her co-researcher for this study, Professor Melissa Hines, of Cambridge University, outlined the findings at a recent conference on the value of toys and play in London. A further study, by researchers in the US state of Georgia, involved rhesus monkeys being offered two categories of toys - one with wheels such as wagons and other vehicles, and the other dolls and cuddly toys including Winnie the Pooh. The male monkeys spent more time playing with the wheeled toys, while the 23 females played with the cuddly and wheeled toys equally. - DM