It’s amazing the things you can find out from the Census. The older census records were created by census takers that went door to door and collected names, occupation, and lots of other goodies. You can find a list of everyone living in the household at the time, their nationality, their parents nationality and lots more.
For the McArdle Side of my family, I looked at the Georgetown Twp Census in 1870 (Census were taken every 10 years)
Listed is Name, Age, Sex, Color, Profession, Value of Real Estate, Value of Personal Property, Place of Birth, Father’s nationality, mother’s nationality, also – attended school, ability to read and write, deaf and dumb, blind, insane, idiotic and so on…. and whether a person is a male citizen 21 years or older (and whether they can vote)
I found three households of McArdles, John, John, and Uriah….
The first John (69 year old Farmer) had $5000 real estate and $1600 personal property – was from Virginia. He lived with Cynthia (20), Martin (22) and Polly (18). Cynthia was listed as Keeping House. I am guessing from the ages Cynthia and Polly were his daughters – but on this I am guessing. They are both listed as from Illinois. Martin is listed as a Farm Laborer from Illinois.
Uriah McArdle (35) is listed next with Mary McArdle (25). Uriah is listed as a Farmer with $400 of real estate and $800 in personal property. He is from Illinois whereas Mary (House Keeper) is listed as from Pennsylvania.
The final household is another John McArdle (30) with Sarah (30). They have two children Lucy (4) and Mary (2) living in the house with them. John is listed as a Farmer with no real estate but $300 of personal property. Sarah is listed as keeping house. They are all listed as from Illinois.
A lot of times the census records are the only record we can find to verify children. Obviously these children and parent all live close together adding to the likelihood that one is the parent of the others and they are all siblings….