Dear Mr. Harrison:
I believe that Geo. W. Harrison was probably my great, great grandmother's (Martha Ann Harrison) brother and that their parents were James Harrison and Eleanor (Ellender) Legg who were married in the District of Columbia on 15 February 1827. I believe that the family broke apart for some reason in the 1840s because Eleanor can be found on both the 1850 census (as Nelly, age 43) and on the 1860 census (as Ellender, age 60?) living in the household of Phebe Gregg.
James Harrison's parents were almost certainly James Harrison (b. ca. 1773) and Cecilia UNK. (b. ca. 1780). This elder James can be found on the 1860 census living in the household of his son-in-law, Thomas Hensey. This family relationship is confirmed by the death record of his wife Cecilia in 1859/60.
If you wish to explore this family further, please contact me by email at firstname.lastname@example.org