There are "givens" - genetic factors - in every individual's physical structure, colouring, shape, size, etc, that can't be changed. Every trait, however, can be encouraged or inhibited to some extent by climate, diet and life-style. The temperament is also based on a set of genetic "givens", tendencies, proclivities and aptitudes. Each of those characteristics, too, can be enhanced and developed or thwarted and repressed.
A quick-tempered, impatient child needs more firm handling and training in self-discipline than an easy-going child, who may require encouragement to make an effort, or a passive one, who needs his confidence bolstered. When a volatile boy is goaded on to action and self-assertion, he's likely to be come a bully; if a timid one is oppressed, he's likely to become a victim.
The outcome is always more or less bad, whenever the natural self-expression is either denied or allowed to run wild.
Parenting is a tightrope act.