I took a look at census for other years.
You need the year of birth for Seymour, William, and Elijah from the census you found. Then, hopefully, you can find them in the 1880 and the 1900 census. In those years they were asked where their parents were born. This information may prove useful.
I checked if Rosina possibly had family in the area. There was only one other Cibbie in all of New York State!
This person had been born in England.
Have you looked at the New York Gen Web Oswego County web site? If your ancestor, Seymour, grew up there it should prove interesting. Put Perkins in the search button which is restricted to the Oswego County web site. Unfortunately, there seems to have been many Perkins families in the county.
When and where were Samuel and Senith born? With the 1930 and 1940 census now out, there could be some information on family offspring which would prove useful in working back.
For instance, a local newspaper obit might list where the person was born and their parents.
I think with the addition of dates, there is more information to be found. Also, remember that New York had census taken in 1855, 1865 etc. I believe family search is in the process of adding these to their database.