While his birth year and age is unknown, John Graham was just a boy in 1578, when his father died. Despite a lack of discussion on the topic, there is some controversy among scholars and historians surrounding the facts and circumstances of this young Earl. John Graham was the child of William Graham, 5th Earl of Menteith, and Margaret Graham (née Douglas). Approximately ten days before his death, William Graham allegedly wrote up a will which turned his son, John Graham, over to the care and charge of his brother-in-law George Buchanan.
His mother, Margaret, began an unsuccessful action in the courts for custody of John Graham, away from the care of George Buchanan. The case was continued on two accounts in 1578, and was never brought to trial, or the records regarding the custody action have been destroyed or are otherwise unavailable. George Buchanan soon died, and young earl John Graham was sent to live with John Graham of Fintry, in the northern part of Menteith. The facts available from the case of Margaret tend to point to a birthdate of 1571 for John Graham, while the facts available in most other sources point to an approximate birthdate of 1574.
James VI of Scotland officially recognized John Graham's claim to the earldom of Menteith in 1583. He would have been 12 years old if born in 1571 and would have been 8 years old if born in 1575. He officially received the lands, despite his minority, in 1587. The young earl requested and received special dispensation from the king to inherit his land before the age of majority, and received those letters of dispensation on 7 October 1587. He was married on 22 October 1587 to Mary, third daughter of Sir Colin Campbell of Glen Orchy.
Upon his receiving the earldom, the same year that he married, he was again in a lawsuit with his mother over certain lands, which she stated were given to her by her husband, William Graham, the 5th Earl, but were now demanded by John Graham of Fintry, who was tutoring the young Earl at that time.
After the lawsuit, a small clash broke out in the lands of Kelwode (Kolwod), where Margaret Graham resided, and the people who brought the fight to Kelwode were the young earl and John Graham of Fintry, along with members of the MacFarland Clan. He would have to be between 11 and 16 years old at the time of the invasion, depending on his correct date of birth. It was later written down as history that the young earl was aware of his mother being in Kelwode, and therefore "was required to find caution that she should suffer no injury". In 1587, the same year of his marriage, and possibly the same year as the attack on Kelwode, he is repeatedly referred to as "scarcely 15 years old", highlighting a further discrepancy in his possible birthdate.
On 6 March 1597, Earl John Graham entered into a rare legal agreement called a mutual bond of maintenance, with Malcom MacFarlane, Feuar of Gartavertane. Mutual bonds of maintenance can be for a multitude of purposes, but are usually extended when one particular clan needed protection from the other, either from famine, or intruders, or to defend and supply one another in a small wars, battles, or sieges. John Graham died shortly thereafter in December 1598.
- William Graham, 7th Earl of Menteith, and
- Christian Graham, who married Sir John Blackadder of Tulliallan, Bt.
- Douglas, David (1909). The Scots Peerage (Founded on Wood's Edition). T.A. and Constable. p. 162.
- Douglas, David (1909). The Scotts Peerage (Founded on Wood's Edition). T.A. and Constable. p. 163.
- Douglas, David (1909). The Scots Peerage (Founded on Wood's Edition). T.A. and Constable. pp. 163–4.
- Burke's Family Records (Indexed), page 565. Accessed via ancestry.com paid subscription site, April 2020.
- Douglas, David (1909). The Scots Peerage (Founded on Wood's Edition). T.A. and Constable. p. 164.
- Calendar State Papers Scotland, vol. 11 (1936), pp. 160-1.