Click to expand/collapse all other details

Male Sylvester Dewey Click to view Sylvester Dewey in the family tree

Sylvester was born on December 7th, 1760 in lebanon, CT.1   Sylvester's father was Abraham Dewey and his mother was Grace Gates.  His paternal grandparents were Josiah Dewey and Sarah Huchinson (Hutchinson); his maternal grandparents were Josiah Gates and Grace Rathbun. He had three brothers and four sisters, and also a sibling of unknown gender, named Abraham, Josiah, Freeman, Lavinia, Submit, Susannah, Amy Grace and Alpheus.  He was the fifth oldest of the nine children.1 

1 phelps.FTW @ Tree #1353
Further sources/citations:
World Family Tree Vol. 1, Ed. 1 @ Tree #3310, phelps.FTW, World Family Tree Vol. 4, Ed. 1 @ Tree #2332, 2332.ftw