This is another one that isn't 100% certain but I think Edward's father Thomas was a victim of a mixup of entries done by the vicar or parish clerk in the 1769 Braddan Parish Register :

There are 3 baptisms for the same day Jan 22 1769:
"Rob't Son of Nic: Gelling & Jane Kelley" [this entry is correct].
"Anne ["Thos" crossed out and replaced with "Anne"] of Jno Cudd & Elizabeth Skillicorn"
"Jane D'r of J'no Gellin & Marg't Caroon".
My theory is that "Thos" belongs to the entry below and the entry for Jno & Eliz Cudd was later corrected.

Reasons for why I think Thomas belongs to this couple:
1. Parents John Gelling & Margaret Caroon married 28 Feb 1767 Braddan. They had 9 children appearing in the Register: John 1767, "Jane" 1769, Robert 1771, Margaret 1773 (d 1774), twins William & Jane 1775, Patrick 1777, Margaret 1778 (d inf), & Ann 1780. The mother died in 1781.
2. Manx Notebook has his mother's admin: "1781-2 E d GELLIN Margaret caroon d 12 aug 1781;7 ch john,thomas,robt,wm.patrick,jane + ann;all ua john caroon + john gelling gfa guardians;husb john;pledges philip creer + patrick gelling both marown;1785 john son arrives la chooses john gelling + robt corlett both braddan supv;inv".
Males in the admin are listed in birth order followed by females in birth order.
3. Father John Gelling Sr of Ballacaine Braddan has son Thos as his executor of his 1822 will. Also mentions sons John £3 & William £5, daughters Jane Gelling £60 + sundry other things, and Ann wife of James Turner £8. A large claim for £200 was made by Isabella Gelling who might be the widow of deceased son Patrick who died 1819.
4. Thomas of Ballanicholas Marown was 82 in the 1851 census and 84 at his burial 19 Jan 1853. Those ages match perfectly to a baptism date 22 Jan 1769.
5. All other Thomas baptisms within 10 years either side of 1769 are definitely not him.
6. No burial found to match to a Jane before the other Jane was born. There was a child "Gellin c/o John Braddan 5 May 1772" but that could be anybody.