Following up on Sandra's info, I will pass along the data I've come across. Maybe you can figure something out from there. Birth certs are usually amended to reflect the child's new name and parents, without divulging bio info. In lieu of a BC try guardianship records....he may not have been legally adopted.

Wm A STETTER b c 1-1865 m Mary KOLB/KOLP b c 1-1867, 11-30-1886 Lancaster Co PA; resided New Castle 1900. They had 1 ch Wm Albert STETTER b 7-3-1889; d 12-25-1959 San Mateo CA; bur Golden Gate Nat'l Cem; m Mary/Maria CLARK c 1908. Wm enl WWI 7-22-1918 from PA; by 1942 his wife is Harriet [marriage not found]. Mary CLARK STETTER b 10-4-1888; d 6-1968 New Castle.
They were either divorced, or he abandoned the family. I could not find him 1920-30-40.
It's possible Leon STETTER/Franklin STARR belonged to Wm/Mary and the family couldn't afford to feed another mouth [or Leon illegitmate], or Wm STETTER was the father [by another person] and dumped him off while he went off to war. Just a scenario to ponder. Of course, Leon may have not belonged to either of them. This may be something you'll never know.

Wm/Mary's dau Margaret STETTER m Harvey STARR s/o Edward/Anna WOODWARD, 4-21-1934 Wilmington, New Castle DE

Franklin B STARR s/o Wm/Annie m Martha/Mattie HINSON b Richmond VA d/o Wm/Jane, 4-3-1888 Lancaster Co Virginia
I thought Edw/Franklin Sr may have been siblings, but they're not.