Where and When was Lawrence born?
The Births and Burials records at the OIOC have no information on Lawrence. But he was probably born somewhere between 1770 and 1775, estimated from his marriage to Mary Lowis in 1794 and that he was a working for the Board of Revenue in 1789 as an assistant and in 1793 as an Examiner, probably not a job for someone less than 16? His marriage has him down as "Inhabitant", which implies that he was in India for some period. Also from the list of Europeans in Bengal (IOR/O/5/26) we know that he was in Bengal from at least 1787. Whether he was elsewhere in India before this we do not know.
From the letters sent by Lawrence from Limerick in 1821 / 1822 trying to sell his commission we have to conclude that either he or his father was from there. Along with the 1814 Letter (see below) from Limerick, the inevitable conclusion is that he or at least his family had some connection to Limerick
Who was Lawrence's father?
We have no information from the summary of the marriage in the India Office Records, nor anything in the military records where we would normally find birth information. It is fairly safe to assume that the fact that he obtained a commission in the British Army even though there was no purchase, he would have to have come from a family with some money if nothing else to have the influence to obtain a commission.
There is a tantalising reference in the War Office: Secretary-at-War, Out-letters (PRO/WO4/516 p 497) which contain letters sent from the War Office relating to the purchase of commissions (amongst other things).
War Office 30 Nov 1814. Sir, In reply to your letter of the 23rd instance. I am directed to acquaint you that by the latest return from the 1st Battalion 56th Regiment dated 25th January 1814. Captain L O'Hara is reported on Command at Bellary in the Presidency of Madras. The above is all the information that can be furnished from this Department. In any further enquiry. I would suggest you applying to the Agents for the Regiment Mssrs Greenwood, Cox and Co. Mr Robert Lukin Asst to Sec. of War Mr W O'Hara Nicholas Street Limerick
One the one-hand it could be just pure coincidence that an O'Hara is enquiring after Lawrence to buy his commission, but is is tempting to think that Mr W O'Hara is in some way related and would give us the long held Irish connection!
A strong possibility to my mind is that the W. O'Hara who was searching for Lawrence is quite likely to be Walter O'Hara b. 1787. He was a freeman of Limerick in 1824 and he later had a military career and was the son of Robert O'Hara of Raheen. More information about him from the Dictionary of Canadian Biography Online. How he could be related is not yet very clear.
John O'Hara (d 1729, Town Mayor of Galway)
1. James O'Hara of Lenaboy (b 1717 d 1787) (county. Galway), Mayor of Galway (1747)
A. James O'Hara of Lenaboy (b 1748. d November 1838, recorder of Galway, Freeman of Limerick 1817)
m. (1796) Margaret Moore (d 1814, daughter of Richard Moore)
i. James O'Hara of Lenaboy (b 1796, d Dec. 1838, recorder of Galway)
m. (15 April 1823) Anne Trench (d March 1870)
B. Robert O'Hara of Raheen Mayor of Galway (1804)
m. Frances Taylor (b 1765)
i. Walter O'Hara (b 1789 d 1871)
ii. Anne Lousia (b 1790 d 1844)
m (25/10/1815) James Hardiman BURKE (b 1788 d 1854)
i. Robert O'Hara Burke (b 1821 d 1861)
iii. John O'Hara (b 1794))
iv. Elizabeth (1799-1875)
m Robert Gregory (b.6/10/1790 d April 1849)
ii. Charles O'Hara (b. 1800 d 1874))
From: http://www.biographi.ca/en/bio/o_hara_walter_10E.html
Walter O'Hara 1789 : Born 1806 : Graduated Dublin 9 March 1809 to 29 November 1810 : 91st Regiment of Foot Ensign 25 March 1811 : 47th Regiment of Foot Lt 6 June 1811 : 7th Caçadores Captain 6 April 1812 : Wounded Badjos 28 July 1813 : 7th Caçadores Btn Major 27 August 1813 : 1st Line Regiment of Foot Major Dec 1813 : Prisoner of War, and Mentioned in Dispatches (Battle of the Nive) Apr 1814 : Leaves Portugese Army 15/12/1816 : Half Pay November 1814 : Limerick 1822 : Marries in London 1824 : Freeman of Limerick 1840 : Emigrates to Canada 1871 : Died Lieut. O'Hara served in the Peninsula with the 59th and was present at the siege of St. Sebastian, and battles of Vittoria, Nivelle, and Nive, for which he has received the War Medal with three Clasps. He served also the Waterloo campaign
Others who may be his father are those actually in India at the time or around the time we think Lawrence was born.
Purely from being of the right age, and taking into account that Lawrence was described as being 'a Gent' on joining the British army the following could potentially be his father.
I have excluded Edward O'Hara who was in the 7th Foot and got his Ensign in the same month as Lawrence (October 1796) in 1807 he became a Major in the Yorkshire Light Infantry, he was born in Canada and is definitely not related to Lawrence see entry in other O'Hara's in India.
Is there anyone who might have been Lawrence's sibling?
If we can't find out from the paper records who Lawrences' father was, then we might be able to find mention of him in related records.
Lawrence's family
He married Mary Lowis previously Skardon, (nee Woodson) see his record for more details.
Who were Lawrence's children
We know that Lawrence had at least 5 children,
It is unlikely that Mary was the mother of any of these children, she would have been over 50 to have given birth to John Lawrence. We know that Elizabeth was a legitimate daughter, so it is very likely that he married again, George was conceived in Mauritius, so his wife who bore him John and Elizabeth was most likely dead by 1820.