Here are a few things I found. There are two marriage records for John and Myrtle in Pike Co, KY. Did they divorce and then remarry?
Kentucky Marriages, 1851-1900 about MERTIE CHILDERS Name: JOHN W. RATLIFF Spouse: MERTIE CHILDERS Marriage Date: 2 Aug 1893 County: Pike State: KY
Kentucky Marriages, 1851-1900 about MYRTIE [Mrs] CHILDERS Name: JNO. W. RATLIFF Spouse: MYRTIE [Mrs] CHILDERS Marriage Date: 14 Nov 1894 County: Pike State: KY
Here's a likely match from the 1880 Pike Co, KY census.
1880 Federal census: Census Place Marrowbone Creek, Pike, Kentucky Family History Library Film1254439 NA Film NumberT9-0439 Page Number622C
NameRelation Marital Status Gender Race Age Birthplace Occupation Father's Birthplace Mother's Birthplace Polly CHILDRESSSelfWFemaleW61KYFarmeressKYVA Victoria CHILDRESSDauSFemaleW10KYAt HomeVAKY Mytie CHILDRESSGDauSFemaleW5KYKYKY
It's going to be hard to figure out the parents for Myttle if the above record is her. Do you have a copy of her death certificate? It may give the names of her parents. Someone has posted information on this Childress family on Rootsweb's World connect. Unfortunately there's no mention of Myrtle.