As I attempt to put the wraps on the Keeling family, I am currently dealing with one of the daughters. Ann's birth is given as 1618, 1630, 1634-38, the 1640s, or 1650, depending on the undocumented source. Her first husband was born about 1616, so that complicates matters a bit!
Some digging turned up the fact that Ann was John Martin's third wife. That sheds some light on the subject! She could have been a number of years his junior.
Ann married twice after John Martin died. The births of hubbies #2 & #3 are estimated at about 1630 and 1638-40. This also sheds a bit more light on the subject.
Examining the possible birth years for Ann, we can rule out 1618. Her mother was born in the 1613-1618 range.
1630? Very much a long short. Her parents arrived in Virginia in 1635. Her father had been in the colony from 1628-1634. Thomas Keeling was granted 100 acres for transporting two persons to Virginia in 1635 - himself and his wife. That would place serious doubt on Ann being born before 1635.
Let's go to the other extreme - 1650. Ann would have been 15/6 when she married Martin about 1665/6. [He died by May 1664 and fathered a son by Ann.] At the time, that was a young age for a girl to marry. Her husband would have been 34 years her senior.
Ann's other husbands were born between 1630 and 1640. So, there's a good chance she was born during that decade as well. She had children with her 1st and 2nd husbands. By 1665, Ann was nearing the end of childbearing years, if born in 1618. If born between 1635 and 1640, she was between 25 and 30. [Childbearing years.]
Based on the clues available, I would estimate Ann's birth between 1635 and 1644. That would make her between 21 and 30 when she married for the first time.
Ann died about 1672.