What are other factor(s) in children's lives that influence their behavior beyond birth order?

A) heredity
B) models of competency or incompetency that parents present to children on a daily basis
C) peer influences
D) All of these.

All three factors (heredity, parental modeling, and peer influences) can have significant effects on a child's behavior, beyond just their birth order. Heredity can influence temperament and personality traits, while parental modeling can shape a child's beliefs and values about competence and success. Peer influences can also play a major role in shaping a child's behavior, particularly as they get older and spend more time with their peers outside of the family dynamic.