"Related" means any of the following relationships by blood, marriage, or adoption: parent, grandparent, sibling, great-grandparent, great-uncle, great-aunt, brother, sister, stepparent, stepbrother, stepsister, uncle, aunt, nephew, niece, or first cousin. (Section 2.04 of the Child Care Act of 1969 [225 ILCS 10/2.04]) (R 406)