Hi Jenny,
I also descend from a George Tincknell from Wedmore, Somerset, England. Probably not the same one, though. Mine b. abt 1821-23 and married Elizabeth (Betsey) Roper 22 July 1843. I am still trying to figure out his parents--looks like his mother was probably Ann Tincknell Bartlett (m Charles Bartlett 1822) and his father is listed as Zebedee Padfield on the parish marriage record. George and Betsey Tincknell emigrated 10 Jul 1848 from Bristol on the ship Romance and settled first in Burlington, Racine Co, WI and in 1853 moved to the Dyersville, IA area. Are there any similarities with your line?