NameJonas Bowen Jr. 
Birthabout 1678
Death25 December 17281436
Parent-Proof notes for Jonas Bowen Jr.
Jonas Jr. is mentioned in his father’s will and said by Robert Barnes to be the son of Jonas Sr. The question though is whether his mother was the first or second wife of Jonas Sr. The name of the first wife is not known but it is known that she was the daughter of Lewis Bryan. The name of his second wife was Martha Henchman, daughter of Nathaniel.
My arguments are presented elsewhere, but my conclusion is that Jonas Jr.’s mother was the daughter of Lewis Bryan.
My Comments notes for Jonas Bowen Jr.
Jonas is known to be the son of Jonas by analysis of any number of early Maryland wills. He is mentioned in both his father's and mother's will as their son. The will of his brother-in-law James Robinson appoints Jonas Bowen Sr. and Jonas Bowen Jr. as Overseers.
Jonas Bowen is listed on the 1699, 1700 and 1701 tax lists of Baltimore County, always on the North side of Patapsco Hundred.
St Paul’s Church records show the death of Jonas Bowen 25 Dec 1728.
The will of Jonas Bowen, planter, Baltimore County, dated 12 Dec 1728 probated 4 Feb 1729 leaves plantation to wife Ann and personalty to her, during widowhood, and if she remarries to daughter Martha Lynch. Also mentions daughter Rebecca Gray, granddaughter Martha Lynch, son-in-law Patrick Lynch and cousin Jonas son of John Bowen. Benjamin Bowen was a witness.
Prerogative court records of Jan 1729 show payment to Patrick Lynch, husband of Martha.
Robert Barnes says that Jonas Jr. was the son of Jonas Sr. and second wife Martha. The question is what evidence is there that Jonas Jr. was indeed the son of second wife Martha and not his first wife. It would be useful to have hard dates associated with the different marriage and birth events for the players in this story -- but they are hard to come by.
I think what evidence there is may mainly be the 1676 will of Lewis Bryan. It leaves 100 acre Bryan’s Forest to Eliza, dau. of Jonas Bowen. No other child of Jonas is named. The will does not say specifically that Eliza’s mother had died. My theory is she had not died but that she had not yet had Jonas Jr. so he is not mentioned. I believe Jonas Jr. was born after 1676 to Lewis’ daughter, whose name we do not know.
The case that he is the son of second wife Martha is harder to make, in my opinion. Martha appears to be the daughter of Nathaniel Henchman’s wife Margaret. His 1694 will provides for her issue including Benjamin Bowen, not yet 18 and Rebecca Bowen. It makes no mention of any other children of Jonas Bowen -- specifically no mention of Jonas Jr.
When Martha writes her will in 1703, she mentions all of Jonas’ known children and his Robinson grandchildren -- they were the children of daughter Eliza, known to be of Jonas’ first wife. In other words, she made no distinction between her issue and that of Jonas’ first wife.
In 1703, Jonas Jr., Benjamin and Martha were of age and John and Onner were not yet of age. So I think the timing was that Jonas Jr. was born in about 1678, son of Jonas’ first wife. Then she died soon thereafter and Jonas married Martha daughter of Margaret, wife of Nathaniel Henchman and she had children Benjamin and Rebecca (also known as Martha) before 1694 (in fact in both cases in the early 1680’s) and John and Onner after. The 1695 will of Nathaniel Henchman does not mention Jonas but does mention Benjamin. Clearly, Jonas was alive in 1695, so why isn’t Jonas mentioned? I believe he was a half-brother to Benjamin, both sons of Jonas by different wives.
My Comments notes for Ann (Spouse 1)
Robert W Barnes says: ”Jonas, son of Jonas and Martha died Baltimore County by 4 Feb 1729, having married Ann, possibly the widow of Roger Reeves. Ann survived Jonas and later may have married Jonas Hewling 20 Dec 1732.”