Hi, A lot of folk have been trying to take that family line back further and discover where in Ireland Patrick Sinnott/Sinnett b 1752 was from, with not much success. However, there is now a DNA study (at familytreeDNA.com) that might help - if you can find a male descendant with a direct father-son line back to Patrick then it would be really great to encourage them to take the Y-DNA37 test at familytreeDNA.com. If this test is ordered through the Sennett/Sinnott surname project then it is at the discounted rate. Doing the test through the surname project also means that I will be able to help match family trees with other project members and try to find any connections with other documented family groups.
If this person tests with an E-L117 haplogroup, then there is a fairly strong chance that Patrick will be part of the main Co Wexford line of Sinnotts that goes back (with some gaps) to anglo-norman origins (arrived in Co Wexford from Wales in the 12th century). But, there is no way of knowing this without someone taking the Y-DNA test.
Recommended test is Y-DNA37, but if money is a problem, then a test with less markers (25 or even 12) will still be useful (and can be upgraded later if required).