With his baptismal record elusive, Venning's date of birth may be calculated from his age at death in 1674 of fifty-three. We can, however, be more precise as to where he spent his early life. Historians, including such eminent scholars as Patrick Collinson and David Underdown, have noted the importance of local identity and environment in the development of puritanism. However, what constituted one's sense of identity in the seventeenth century is still a matter of debate: whether loyalties were provincial, national or, even, international – identifying oneself with the elect of Christ's universal Church. This complexity is reflected by the Devonshire diarist, Sir Walter Yonge (1579–1649), a county gentleman of puritan sympathies. Indeed, in seventeenth-century Devon, Mark Stoyle has argued that, because of the landscape and issues of travel, identity was shaped by more local influences even than one's county. In order to understand Venning, then, it is of some value that we consider where it was that he grew up.

In his biography, Prince identified Alwington or Allington near Bideford in north-west Devon as the area in which Venning's family lived, having known Venning's brother there while a curate in Bideford. However, although Venning's brother may have settled there and been known to Prince, there is no evidence of Venning's family amongst parish records, neither for Allington nor Bideford. There were, in fact, a number of Vennings in nearby Buckland Brewer, although no reference to Ralph's family. On the other hand, Kingsteignton in east Devon has been proposed as his place of birth, while Stephen Wright's revised entry for the Dictionary of National Biography is noncommittal, simply giving ‘Devon’.

Instead, evidence suggests that Lamerton in the Hundred of Lifton, Deanery of Tavistock, is where Venning spent his early life. Although there is no record of his baptism in the Lamerton records either, his father's will, proved at the Consistory Court in London in 1658, describes Francis Venning as a yeoman of that parish, with tenement property in nearby Tavistock. The family also owned property – a tenement – in North Brentor, within Lamerton parish, and a share in Broadmead Meadow.