From George's marriage cert or death cert both online - his parents are Frank (Francis) Stanley and Margaret Jennings.Further search of Frank and Margaret locates his birth record, fathers birth record, siblings etc.probably more if you plug in individual names.
All from familysearch.org.Examples below:
Not my family, good luck.
Massachusetts Marriages, 1841-1915 4332430 Image187 Name: George W. Stanley Residence: 18 Essex St. Occupation: Freight Handler Event: Marriage Event Date: 16 Jun 1903 Event Place: Boston, Suffolk, Massachusetts Gender: Male Age: 28 Marital Status: 1st Birthplace: Ireland Marriage Registration Year: 1903 Marriage Registration Place: Boston, MA Estimated Birth Year: 1875 Father: Frank Stanley Mother: Margaret Jennings Spouse: Mary Black Age: 27 Spouse's Titles & Terms: Cook Spouse's Residence: 4 NashRow Spouse's Marital Status: 1st Spouse's Father: Andrew Black Spouse's Mother: Jane Whitefield Record Number: 33 Film Number: 2057589 Digital Folder Number: 4332430 Image Number: 00229 Number of Images:
Name: George Stanley Titles & Terms: Event: Death Event Date: 11 Jan 1907 Event Place: Boston,,Massachusetts Residence: Boston, MA Street Address: 135 High St Gender: Male Age: 33 yrs 5 mos 1 day Marital Status: Married Birth Date: 1874 Birthplace: Ireland Estimated Birth Year: 1874 Burial Place: Everett, MA Cemetery: WoodLawn Father: Frank Stanley Father's Birthplace: Ireland Mother: Margaret Jennings Mother's Birthplace: Ireland Volume/Page/Certificate Number: 409 Film Number: 2258664 Frame Number: Digital Folder Number: 4283023 Image Number: 01226
Ireland Births and Baptisms
Name: Francis Stanley Gender: Male Birth Date: 14 Apr 1865 Birthplace: 0278,BALLINEEN,CORK,IRELAND Father's Name: William Stanley Mother's Name: Jane Stanley Indexing Project (Batch) Number: C70126-1 System Origin: Ireland-ODM Source Film Number: 101109 Reference Number:
Name: Eliza Gender: Female Baptism/Christening Place: 299, BALLYNEEN, CORK, IRE Birth Date: 09 Feb 1871 Birthplace: Ballyneen, Cork, Ire Father's Name: Francis Stanley Mother's Name: Margaret Jennings Indexing Project (Batch) Number: C70144-7 System Origin: Ireland-VR Source Film Number: 255816 Reference Number: - 2:27G0LLS
Name: George Stanley Gender: Male Birth Date: 09 Aug 1872 Birthplace: Cork, Ireland Father's Name: Francis Stanley Mother's Name: Margaret Jennings Indexing Project (Batch) Number: C70150-4 System Origin: Ireland-EASy Source Film Number: 255860 Reference Number: v 15 p 222