There are a few Sidney's listed in phone Directories in St Louis, MO
that might be related most born 1950's.
Ancestors you will have to wait until 2012 for 1940 census to be released.
good luck in your search

Name: Ester T Sidney
Service Info.: SN US NAVY KOREA
Birth Date: 12 May 1937
Death Date: 3 Aug 1998
Service Start Date: 25 Jan 1955
Interment Date: 10 Aug 1998
Cemetery: Jefferson Barracks National Cemetery
Cemetery Address: 2900 Sheridan Road St. Louis, MO 63125
Buried At: Section Zz Site 1021

Name: Ester Sidney
SSN: 410-46-3095
Last Residence: 63107 Saint Louis, Saint Louis City, Missouri
Born: 12 May 1937
Died: 15 Aug 1998
State (Year) SSN issued: Tennessee (Before 1951)

us phone address directory 1993-2002
Name: Ester Sidney
Address: 3957 Lexington Ave
City: Saint Louis
State: Missouri
Zip Code: 63107-2012
Phone Number: 314-533-3213
Residence Years: 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
(possible wife or children continued to live in residence after he died?)

us records vol 1
Name: Ester Sidney
Birth Date: 12 May 1937
Address: 3957 Lexington Ave, Saint Louis, MO, 63107-2012 (1985)

vol 2
Name: Ester Sidney
Birth Date: 12 May 1937
Address: 812 Henderson Pl, Memphis, TN, 38126