AITF was the American adaption of a British series Til Death Do Us Part. The premise is almost exactly the same. Working class families with a very conservative head, liberal son in law, spouses were about the same as well.
The only real differences were time frames. Til Death Do Us Part dealt with Post WWII Great Britain, unions, immigration, politics. All in the Family focused on the late 60s early 70s issues, Viet Nam, racism, feminism, etc
I think Lear probably had to be a bit cynical to insure some comedic value