Jenkins was born in 1929 into a Welsh-speaking "seafaring" family based near Llangrannog in Ceredigion; he attended the village school and Cardigan Grammar School, before completing his university education at the University Colleges of Wales at Swansea and Aberystwyth.
But his move back to St Fagans and the Folk Museum in 1987 to be its Curator was less happy, owing in part to clashes with management and what Jenkins regarded as English interference.
He was the High Sheriff of Dyfed in 1994–95 and joined Ceredigion County Council, serving as its Chairman in 2002–03.
[1] According to his obituary in The Independent, "Geraint Jenkins played a leading role in the preservation and interpretation of the maritime history of Wales.
He also made expert studies of other aspects of Welsh folk life, including traditional farm implements, rural crafts, the woollen industry and Cardiff ship-owners.