Little girls like dolls and little boys prefer toy cars. Is this a natural instinct or a choice under the influence of the environment the day after tomorrow? In an experiment, researchers observed the preferences of infants aged 3 ~ 8 months for toys and found that female infants stared at pink dolls longer than toy trucks, while male infants focused more on blue trucks. 
The different placement of toy trucks and dolls will affect the baby's attention
 the researchers believe that infants' different preferences for toys may be determined by gender genes.