Virtually all members belong to the Y-DNA haplogroup R-U106>>L47>Z160>CTS3777>FGC17298>FGC17304>BY60604>FT85154, showing we descend from one man called BLOOD or BLUD who lived about 1400 AD.
This paternal ancestor lived in the midlands of England, probably around Marston-on-Dove in Derbyshire (see https://blood.one-name.net/). There are other branches of the surname from the 1500s and 1600s in Staffordshire, Leicester, Lincolnshire and Shropshire , most of which are yet to be verified as the same family.
As well, very early mentions of BLOD are found in documents from the 1200s in Northumberland and Worcestershire. - see
Around 1585 a soldier, Edmund Blood of Duffield Derbyshire, proceeded to Ireland where he established a line of Irish Bloods of some eminence and wealth, including the infamous Thomas Blood who stole the crown jewels. This line is very well documented in the book of Bindon Blood, but it may now be extinct.
In the 1630s and 1640s four relatives called Blood emigrated to the New World from Nottinghamshire. The lines of two of these men, Richard and Robert Blood, became very substantial with in excess of 4000 BLOODs present in New England in 1900. Most of the research on these two Massachusetts families comes by way of a book called "The Story of the Bloods" by Roger Dean Harris. One of the admins of this project is descended from Robert.
In the 1800s other men from Nottingham, Derbyshire and Staffordshire emigrated to the USA and Australia, and Joe Flood is descended from one of these.
Trees for these various families are to be found on https://wc.rootsweb.ancestry.com/; databases richardblood, robertblood, staffordbloods, derbybloods, outerbloods, thepeerage