"Temperamental traits" refers to the natural tendencies or behaviors that a person or thing commonly exhibits, which can sometimes be unpredictable or changeable. Full definition
In other words, preschool - age children's temperamental traits meaningfully predict their later personalities, but there is also good evidence that children do still change across the childhood and adolescent years. (child-encyclopedia.com)
Considering the rapid pace of development during the first years of life, it is not surprising that children's temperamental traits show only modest stability during infancy and toddlerhood and then show a rather large increase in stability by around age three. (child-encyclopedia.com)
The association of 5 - HTTLPR and DRD VNTR polymorphisms with affective temperamental traits in healthy volunteers (cambridge.org)