When was Lawrence's 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 an 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 we know that he was in Bengal from at least 1787.
Who was Lawrence's father?
There is a tantalising reference in the War Office: Secretary-at-War, Out-letters (Ref 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, possibly a brother or even his father.
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, the following could potentially be his father.
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.
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 defintely not related to Lawrence see entry in other O'Hara's in India.
Lawrence's family
He married Mary Lowis (nee Woodson) see his record for more details.
Who were Lawrence's children
We know definitely that Lawrence had at least 2 children,
I am hypothesising another two: the lack of any baptism details may indicate that they were a. not by Mary or b. lost amongst the 15-20% of records not received in London.
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.