Alan seems to love and accept his sons without reserve, although he claims to have realized when Charlie was eight that he had nothing left to teach his youngest son about math. He is a (generally) non-practicing Jew, and has, along with the boys' mother, a long history of involvement in civil rights and even anti-government protests, which is an occasional source of friction with Don. He has, however, passed on his love of sports to his eldest son, and the two men often bond over basketball or baseball.
Seemingly by both training and inclination, Alan is an engineer and planner. When the series begins he is retired, but like many people his savings take a severe financial hit, and Alan finds himself needing to re-enter the job market. He also goes back to school, at CalSci, to brush up his skills, and pursue new avenues of intellectual interest. One of these turns out to be, or at least intimately involve, Charlie's new boss.
Alan is the everyman to Don's guardian of the law and Charlie's ivory tower intellectual, but he has the compassion and moral compass visible in both his sons. These qualities, by all accounts, were shared with his wife, but since she passed away he has kept his family together. Alan is also an ardent defender of civil rights, and occasionally butts heads with his eldest son over what is permissible in defense of the general good, although the two almost always maintain mutual respect.