Hi, I'm English so not great at searching american records but I do have ancestry.
There is one tree on ancestry that is public and looks well researched. It is called The Moon family tree if that means anything to you?
Anyway this user has Johns parents as Daniel Coffman born 1791 in Pennsylvania and Mary Walthen born 1794 in Pennsylvania.
The siblings of John are different, they are listed as Daniel P born 1826 and Mary E born 1830.
The 1830 and 40 census are included but don't offer much insight as they only list the name of the head of household, the children are just listed as number of 'free white persons living at address'. In 1840 the detail looks like this, (so there probably are more siblings)
|Home in 1840 (City, County, State)
||Perry, Saint Francois, Missouri|
|Free White Persons - Males - 5 thru 9
|Free White Persons - Males - 10 thru 14
|Free White Persons - Males - 15 thru 19
|Free White Persons - Males - 50 thru 59
|Free White Persons - Females - 10 thru 14
|Free White Persons - Females - 20 thru 29
|Free White Persons - Females - 40 thru 49
|Persons Employed in Agriculture
|Free White Persons - Under 20
|Free White Persons - 20 thru 49
|Total Free White Persons
|Total All Persons - Free White, Free Colored, Slaves|