Their father was a Thomas BYRAM, and his parents were Abraham BYRAM and Dorothy CLAY.Interesting aspect is that Dorothy had a son named Thomas BEFORE marrying Abraham.It is undetermined if there were 2 Thomas' here.One thought is there was Thomas CLAY Byram whom Abraham adopted AND THomas Byram, Abraham's biological son.Most researchers believe there was only 1 Thomas - THomas CLAY Byram - son of Dorothy and a man named ?? CLAY.This, of course, would mean that we are not descended from Abraham, but are really descended from Thomas biological father - a CLAY.
Be advised that I have NOT verified this information personally.Do not take it as fact, please.However, we DO know that Thomas was the father of the 3 men you mentioned, and that Dorothy DID have a son Thomas before marrying Abraham.I descend from Cuthbert's son George, and George's son Simon, who migrated to Sumner County, TN.
A good book to have is "Byrams in America" by John Byram.