diff --git a/app/models/concerns/nameable.rb b/app/models/concerns/nameable.rb
index 8e54efd..5775859 100644
--- a/app/models/concerns/nameable.rb
+++ b/app/models/concerns/nameable.rb
@@ -6,16 +6,17 @@ module Nameable
   included do
     pg_enum :sex, %i[male female]
 
-    before_validation :turn_blank_middle_name_into_nil
+    before_validation :turn_blank_nameable_attributes_into_nils
 
+    validates :last_name,  presence: true
     validates :first_name, presence: true
-    validates :last_name, presence: true
-    validates :sex, presence: true
-    validates :date_of_birth, presence: true
-    validates :place_of_birth, presence: true
   end
 
-  def turn_blank_middle_name_into_nil
-    self.middle_name = nil if middle_name.blank?
+  def turn_blank_nameable_attributes_into_nils
+    %i[
+      last_name first_name middle_name sex date_of_birth place_of_birth
+    ].each do |attribute|
+      public_send "#{attribute}=", nil if public_send(attribute).blank?
+    end
   end
 end
diff --git a/app/models/concerns/required_nameable.rb b/app/models/concerns/required_nameable.rb
new file mode 100644
index 0000000..fc84a26
--- /dev/null
+++ b/app/models/concerns/required_nameable.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module RequiredNameable
+  extend ActiveSupport::Concern
+
+  include Nameable
+
+  included do
+    validates :sex,            presence: true
+    validates :date_of_birth,  presence: true
+    validates :place_of_birth, presence: true
+  end
+end
diff --git a/app/models/passport.rb b/app/models/passport.rb
index e8556af..a872d83 100644
--- a/app/models/passport.rb
+++ b/app/models/passport.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class Passport < ApplicationRecord
-  include Nameable
+  include RequiredNameable
 
   FORMAT_RE = /\A[^[:space:]]+(.*[^[:space:]]+)?\z/.freeze
 
diff --git a/app/views/staffs/people/index.html.erb b/app/views/staffs/people/index.html.erb
index 70bde6a..cee8567 100644
--- a/app/views/staffs/people/index.html.erb
+++ b/app/views/staffs/people/index.html.erb
@@ -32,10 +32,12 @@
           <td><%= truncate person.middle_name, length: 15 %></td>
           <td><%= truncate person.last_name, length: 15 %></td>
           <td class="d-none d-lg-table-cell">
-            <%= localize person.date_of_birth %>
+            <%= localize person.date_of_birth if person.date_of_birth %>
           </td>
           <td class="d-none d-md-table-cell">
-            <%= truncate person.place_of_birth, length: 15 %>
+            <% if person.place_of_birth %>
+              <%= truncate person.place_of_birth, length: 15 %>
+            <% end %>
           </td>
           <td>
             <% if policy([:staff, person]).show? %>
diff --git a/app/views/staffs/people/show.html.erb b/app/views/staffs/people/show.html.erb
index 7137f1b..0240380 100644
--- a/app/views/staffs/people/show.html.erb
+++ b/app/views/staffs/people/show.html.erb
@@ -12,13 +12,13 @@
     <dd><%= truncate @person.last_name %></dd>
 
     <dt><%= Person.human_attribute_name :sex %></dt>
-    <dd><%= translate_enum :sex, @person.sex %></dd>
+    <dd><%= translate_enum :sex, @person.sex if @person.sex %></dd>
 
     <dt><%= Person.human_attribute_name :date_of_birth %></dt>
-    <dd><%= localize @person.date_of_birth %></dd>
+    <dd><%= localize @person.date_of_birth if @person.date_of_birth %></dd>
 
     <dt><%= Person.human_attribute_name :place_of_birth %></dt>
-    <dd><%= truncate @person.place_of_birth %></dd>
+    <dd><%= truncate @person.place_of_birth if @person.place_of_birth %></dd>
 
     <dt><%= Person.human_attribute_name :current_regional_office %></dt>
     <dd>
diff --git a/db/migrate/20181129203927_initial_migration.rb b/db/migrate/20181129203927_initial_migration.rb
index 9254262..ddcaf21 100644
--- a/db/migrate/20181129203927_initial_migration.rb
+++ b/db/migrate/20181129203927_initial_migration.rb
@@ -102,9 +102,9 @@ class InitialMigration < ActiveRecord::Migration[6.0]
       t.string :first_name,     null: false
       t.string :middle_name,    null: true
       t.string :last_name,      null: false
-      t.column :sex, :sex,      null: false
-      t.date   :date_of_birth,  null: false
-      t.string :place_of_birth, null: false
+      t.column :sex, :sex,      null: true
+      t.date   :date_of_birth,  null: true
+      t.string :place_of_birth, null: true
 
       t.references :contacts_list,
                    null: false, index: { unique: true }, foreign_key: true
diff --git a/db/structure.sql b/db/structure.sql
index 65f9247..000da81 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -459,9 +459,9 @@ CREATE TABLE public.people (
     first_name character varying NOT NULL,
     middle_name character varying,
     last_name character varying NOT NULL,
-    sex public.sex NOT NULL,
-    date_of_birth date NOT NULL,
-    place_of_birth character varying NOT NULL,
+    sex public.sex,
+    date_of_birth date,
+    place_of_birth character varying,
     contacts_list_id bigint NOT NULL
 );
 
diff --git a/spec/models/passport_spec.rb b/spec/models/passport_spec.rb
index 34a5fb3..7a56602 100644
--- a/spec/models/passport_spec.rb
+++ b/spec/models/passport_spec.rb
@@ -5,7 +5,7 @@ require 'rails_helper'
 RSpec.describe Passport do
   subject { create :empty_passport }
 
-  it_behaves_like 'nameable'
+  it_behaves_like 'required_nameable'
 
   describe '#person' do
     it { is_expected.to belong_to(:person).optional }
diff --git a/spec/models/shared_examples/nameable.rb b/spec/models/shared_examples/nameable.rb
index cc721ec..e60c0aa 100644
--- a/spec/models/shared_examples/nameable.rb
+++ b/spec/models/shared_examples/nameable.rb
@@ -1,27 +1,40 @@
 # frozen_string_literal: true
 
 RSpec.shared_examples 'nameable' do
-  it { is_expected.to validate_presence_of :first_name }
+  it { is_expected.to     validate_presence_of :last_name }
+  it { is_expected.to     validate_presence_of :first_name }
   it { is_expected.not_to validate_presence_of :middle_name }
-  it { is_expected.to validate_presence_of :last_name }
-  it { is_expected.to validate_presence_of :sex }
-  it { is_expected.to validate_presence_of :date_of_birth }
-  it { is_expected.to validate_presence_of :place_of_birth }
+  it { is_expected.not_to validate_presence_of :sex }
+  it { is_expected.not_to validate_presence_of :date_of_birth }
+  it { is_expected.not_to validate_presence_of :place_of_birth }
 
-  describe '#middle_name' do
-    context 'when it is empty' do
-      subject { create :member_person, middle_name: '' }
+  %i[
+    last_name
+    first_name
+    middle_name
+    sex
+    date_of_birth
+    place_of_birth
+  ].each do |attribute|
+    describe "##{attribute}" do
+      context 'when it is empty' do
+        subject { build :member_person, attribute => '' }
 
-      specify do
-        expect(subject.middle_name).to eq nil
+        before { subject.validate }
+
+        specify do
+          expect(subject.public_send(attribute)).to eq nil
+        end
       end
-    end
 
-    context 'when it is blank' do
-      subject { create :member_person, middle_name: '   ' }
+      context 'when it is blank' do
+        subject { build :member_person, attribute => '   ' }
 
-      specify do
-        expect(subject.middle_name).to eq nil
+        before { subject.validate }
+
+        specify do
+          expect(subject.public_send(attribute)).to eq nil
+        end
       end
     end
   end
diff --git a/spec/models/shared_examples/required_nameable.rb b/spec/models/shared_examples/required_nameable.rb
new file mode 100644
index 0000000..308a20a
--- /dev/null
+++ b/spec/models/shared_examples/required_nameable.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+RSpec.shared_examples 'required_nameable' do
+  it { is_expected.to     validate_presence_of :last_name }
+  it { is_expected.to     validate_presence_of :first_name }
+  it { is_expected.not_to validate_presence_of :middle_name }
+  it { is_expected.to     validate_presence_of :sex }
+  it { is_expected.to     validate_presence_of :date_of_birth }
+  it { is_expected.to     validate_presence_of :place_of_birth }
+
+  %i[
+    last_name
+    first_name
+    middle_name
+    sex
+    date_of_birth
+    place_of_birth
+  ].each do |attribute|
+    describe "##{attribute}" do
+      context 'when it is empty' do
+        subject { build :member_person, attribute => '' }
+
+        before { subject.validate }
+
+        specify do
+          expect(subject.public_send(attribute)).to eq nil
+        end
+      end
+
+      context 'when it is blank' do
+        subject { build :member_person, attribute => '   ' }
+
+        before { subject.validate }
+
+        specify do
+          expect(subject.public_send(attribute)).to eq nil
+        end
+      end
+    end
+  end
+end
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index 532c433..1ada015 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -38,6 +38,7 @@ require_relative 'support/devise'
 require_relative 'support/pundit'
 
 require_relative 'models/shared_examples/nameable'
+require_relative 'models/shared_examples/required_nameable'
 
 # Checks for pending migrations and applies them before tests are run.
 # If you are not using ActiveRecord, you can remove these lines.