1. Whisk together flour, ginger, cinnamon, baking soda, nutmeg, and salt in a medium bowl.
2. Sift brown sugar sugar into a large bowl and beat in butter with an electric mixer until fluffy. Add egg yolks, beating, 1 at a time until well combined. Beat in molasses until combined well. Slowly add flour mixture, beating on low speed until just combined.
3. Turn dough out onto a lightly floured surface and knead until it just comes together. Quarter and form into disks. Wrap each in plastic and chill until firm, about 1 hour.
4. Preheat oven to 350 degree F and line 4 large cookie sheets with parchment.
5. Roll 1 disk of dough between 2 sheets of waxed paper until 1/4 inch thick. Cut out gingerbread family with cookie cutters (if dough is too soft at any point, re-chill until firm), gather scraps of dough into a disk and re-chill until firm. Transfer cutouts to prepared cookie sheets and chill until firm. Repeat rolling, cutting, and chilling remaining dough and dough scraps in same manner.
6. Bake cookies, in batches, in upper and lower thirds of oven until golden brown, 10 to 12 minutes. Transfer cookies on sheets to a wire rack to cool until firm.
7. Cookies will keep for 3 weeks stored between sheets of waxed paper in an airtight container. Makes about 3 dozen cookies including small and large.