(a) Except as otherwise provided in subdivision (b), a prospective adoptive parent or parents shall be at least 10 years older than the child.
(b) If the court is satisfied that the adoption of a child by a stepparent, or by a sister, brother, aunt, uncle, or first cousin and, if that person is married, by that person and that person’s spouse, is in the best interest of the parties and is in the public interest, it may approve the adoption without regard to the ages of the child and the prospective adoptive parent or parents.