The Tweed family - comprising seven brothers and five sisters - made history after months of Guinness World Records checks.
The siblings, brought up in Coventry, England, are aged between 76 and 95 and between them have 33 grandchildren, 59 great-grandchildren and 17 great-great-grandchildren, 'mirror.Co.Uk' reported.
They are Elsie, 95, Reginald, 92, Robert, 91, Cynthia, 89, Ralph, 87, Noel, 85, Eric, 83, Ronnie, 82, Malcolm, 81, Valerie, 79, Phyllis, 78, and Eunice 76.
A 1939 photo shows them at their Coventry home with barmaid mum Flo and dad Percy, who had a total of 16 children. Four have since died.
The 12 siblings remain close and meet up every year at family gatherings.