The Genealogical Record of the Barnum Family says he had one son, Isaac Edwin Barnum; The Barnum Family shows two sons, Isaac Barnum and Edwin Barnum.
From the History of Van Buren Co, MI: Edwin Barnum whose portrait is given with this sketch, was born in Mentz, Cayuga Co, NY, Mar 31, 1814 and was fifth in a family of seven children-four sons and three daughters. He assisted in the duties of home until he was 21, and in the spring of 1835 came to PawPaw Twp Van Bauren Co, MI in which he lived with the exception of a few brief periods, until his death, which occurred Aug 24, 1875. Soon after his arrival in the state he located land on sec. 10 in Paw Paw and kept "bachelor's hall" for one year. He boarded during the remaining time until 1840 and on the 21st of March was married to Sarah Ann, daughter of John and Mary Lyle, who had moved from the state of NY in the fall of 1835. Mrs Barnum was born 5 Nov 1828 and was the third in a family of ten children -- 5 sons and 5 daughters. Of these, 8 are now living in Van Buren Co and two in Cass Co, MI. Mr and Mrs Barnum had but one child, Isaac born 19 May 1842. At an early age he evinced extraordinary talent, being of delicate constitution, he adopted the study of the law, in which profession he would have without doubt distinguished himself had his health permitted. He is now in Colorado, seeking a new lease of life among the rocky peaks and pure dry atmosphere of that state. At the age of 29 years, Edwin embraced religion and united with the Christian Church in which he was soon licensed to preach. He labored earnestly in this sparsely-settled region with an acknowledged power of doing good. His purity of life, genial temper, and great kindness of heart made him many friends. In language he was eloquent and in principle correct. He held the office of county treasurer eight consecutive years and filled very acceptably, the office of supervisor several terms. For 32 years he was a consistent member of the Church of Christ. His faithful and devoted wife, now wearing the garb of widowhood, is living in the village of Paw Paw, surrounded by the comforts which she assisted her husband to accumulate.
In the 1850 US Census for Lafayette, Van Buren, Michigan the family of Edwin BARNUM was enumerated as follows:
Household #87; Family #87
Barnum, Edwin; 36; M; Farmer; real estate $2,000; b. New York
Barnum, Sarah; 29; F; b. England
Barnum, Isaac E.; 9; M; b. Michigan; attended school during previous year
'The Barnum Family' says 31 MAR 1814.
'The Barnum Family, 1517-1904' [Source] says 1873.