Details of Isaac's birth are not known.

Isaac married Sarah Greenhough on Wednesday 23 January 1765 in Uttoxeter, Staffordshire.

He had the following children from his marriage to Sarah Greenhough:

- Jonathon Key	born around 1765.
- Charles Key	born around 1766.
- Sampson Key	born around 1768.

Details of Isaac's occupation are not known.