While Atticus is an overtly masculine protagonist, many of his actions do not reflect the machismo of this era. For instance, while other men of the community are hard drinkers, Atticus never reveals any vices of his own, save for the evening newspaper. In addition, Atticus does not conform his children to societal expectations of boys and girls: he lets Scout wear her overalls and be as tomboyish as she desires, and he allows Jem moments of sensitivity that would be thought "unmanly."
Men of this era were also not typically open-minded; Atticus defies this stereotype through his defense of Tom Robinson, and through other actions demonstrated throughout the novel. While he is willing to "put down" a sickened dog by shooting it early on in the novel, he also discourages his children's use of guns to unnecessarily kill harmless or defenseless animals. Most men of this era didn't really care if their kids were shooting at birds of any sort, but Atticus does.
Atticus' lack of gender stereotyping is obvious in how he raises his children. He treats Jem and Scout as equals; when he asks Jem to look after Scout, he does so not because Scout is female but because she is considerably younger than Jem. He never expects Scout to defer to Jem because he is a male member of the household. Also, Atticus cares about Scout's education as much as he cares about Jem's, teaching her to read long before she started school.
Atticus knows Scout is in a tomboy stage of her life and it bothers him not at all. Aunt Alexandra, however, harps constantly that "Jean Louise" (never "Scout"), must be taught to dress and comport herself as a little lady. Atticus listens but does not change Scout's daily lifestyle. Scout recalls that when Alexandra would call her into the living room to meet the ladies of Maycomb, Scout's appearance always caused consternation:
When I appeared in the doorway, Aunty would look as if she regretted her request; I was usually mud-splashed or covered with sand.
Atticus is not concerned with Scout's dress or daintiness; he cares instead that she, like Jem, grows into a strong, compassionate, just, and responsible adult.
Atticus does not force gender stereotypes upon his son, either. During the terrible events of Tom Robinson's trial, Jem was often upset and sometimes heartbroken. He sometimes shed tears of anger, frustration, and pain when witnessing the racism and injustice that surrounded him. Atticus was sensitive to Jem's feelings, never scolding him for his tears or telling him to "act like a man." Atticus treated each of his children as individuals deserving of respect, as well as love.