python - これは NONE を返します。入れ子が間違っていますか?

Question

behavioural_levelraw_input 1、2、または 3 として定義され
ています。ここで何が起こっているのでしょうか?

def summary_behaviour(x):
    if behaviour_level == 1:
        x = random.randint(0,1)
        if x == 0:
            return " "+str(first_name)+" has a rather "+str(shy[random.randint(0,(len(shy)-1))])+" personality. This has certain advantages. One is that "+str(he_she(gender))+" doesn't easily "+str(lose_focus[random.randint(0,(len(lose_focus)-1))])+": however, "+str(he_she(gender))+" can be a litte quiet at times." 
        else:
            if x == 1:
                return " Because of "+str(first_name)+"'s "+str(shy[random.randint(0,len(shy)-1)])+" character "+str(he_she(gender))+" can be a little quiet sometimes. On the plus side, however, "+str(he_she(gender))+" doesn't "+str(lose_focus[random.randint(0,len(lose_focus)-1)])+" very easily."
    elif behaviour_level == 2:
        x = random.randint(2,3)
        if x == 2:
            return str(first_name)+" is usually quite "+str(loud[random.randint(0,(len(loud)-1))])+" in class, and this has advantages and disadvantages. "+str(first_name)+" loves to involved and enjoys speaking, but sometimes "+str(hes_shes(gender))+" too "+str(loud[random.randint(0,(len(loud)-1))])+" to fully concentrate. This is common though. "
        else:
            if x == 3:
                return " Because of "+str(first_name)+"'s "+str(loud[random.randint(0,len(loud)-1)])+" character "+str(he_she(gender))+" is "+str(adjective(int(science_level)))+" at speaking up and volunteering. Occasionally, "+str(his_her(gender))+" "+ str(loud[random.randint(0,len(loud)-1)])+ " nature can cuase "+str(him_her(gender))+ " to "+str(lose_focus[random.randint(0,len(lose_focus)-1)])+" but, that's fairly normal at "+str(his_her(gender))+" age."
    else:
        if behaviour_level == 3:
            x = random.randint(4,5)
            if x == 4:
                return " I would descirbe "+str(fisrt_name)+" as a "+(str(well_mannered[random.randint(0,len(well-mannered)-1)]))+" child who is easy to teach. Rarely is "+str(he_she(gender))+" too "+str(loud[random.randint(0,(len(loud)-1))])+" to focus or too "+str(shy[random.randint(0,(len(shy)-1))])+" too speak up."
            else:
                if x == 5: 
                    return str(first_name)+" a "+ (str(well_ma