The problem, as you are probably aware, is there seems to be more than one Isaac Doughty in NY and the birth years are not completely consistent for any of them. BUT, if you look on the 1875 NY State Census, you will find YOUR Isaac listed in Cazenovia, Madison Co as : Isaac D. 38 b. Dutchess Co, wife Jennie A., 34, b. Madison Co and son Dewitt G, 2-9/12 b. Madison Co. That points us to DUTCHESS County and I only see one Isaac there. In the 1860 Census in Beekman, Dutchess Co, we find Isaac B Doughty, 22, a laborer residing in the home of the Heatherington family (an innkeeper) and then in 1850 in Beekman, Dutchess Co: Isaac Doughty, 18, with parents Peter 43 and Emma 41 along with some siblings. If you look at this 1850 census entry, you will see a number of over-writes on the ages so although Isaac is clearly listed as 18, I'm not sure I completely believe it - as either the enumerator or the person giving the info was a bit confused. Isaac could be a number of years younger and still be in sequence with his siblings. The other Isaacs are not in Dutchess County. I'd put my money on your Isaac being the son of Peter and Emma Doughty of Dutchess County. Does that help? At least it should give you more to follow-up on. Good luck!